IF the US Supreme Court says "X" is a state matter, and the Constitution offers no appeal (to a nonexistent higher court), but a US congressman proposes (or votes for) a federal law about "X," are they violating their oath to support the constitution?
I think you are largely misinterpreting the situation that occurred here. Relevant to the 10th amendment is the supremacy clause, which basically states that in case of conflict between state and federal law, federal law takes precedence. The Supreme Court (in my opinion) correctly ruled that a Supreme Court ruling is not the equivalent of congress making a law and reversed its prior ruling. This then would make any laws currently in place by states in effect, until the US congress makes a law, one way or the other, which in case the supremacy clause would apply once again. Remember the basis of their 2022 judgement is that the legislature, not courts, make laws. So the supremacy clause (which is about laws in vertical jurisdictions) does not apply.
This wouldn't be complete without the counter argument. The counter argument is that there is already federal law that explicitly mentions protections for abortions (citing the 14th amendment). Now given that the 14th amendment is the most litigated law in the world, likely in history, I'm not sure that argument about explicit mention holds much water. When laws are vague, their interpretation falls to the courts. If a court can interpret the law in several, not similar ways, then it's safe to assume that there is reasonable doubt about something actually being in the law. For context, the relevant portions in the 14th which was used in support of the original interpretation for the Roe v. Wade case:
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
Which as you can see, doesn't mention abortion so the argument first raises the question, "does this apply to abortion?" (which was not really a widespread thing in the 1860s). Since many judges fall into the literalist or originalist camps (to interpret laws to the letter of the law explicitly or to interpret the law to the intent of the drafters, respectively), you can likely see where judges would say this has nothing to do with abortion and should not have been used in support of a ruling on abortion.
A branch of the U.S. government acting to thwart the actions of another branch of the U.S. government is a feature, not a bug.
So is it a violation of a lawmaker's oath to the Constitution (that they will support and defend it against all enemies, foreign and domestic) to use the powers delegated to them in that same document? No.
The oath to the Constitution (against all enemies, foreign and domestic) commits those who swear it to actively thwart efforts to subvert or overthrow the democratic (small-d) government and system of laws of the United States of America.
By definition, any act of Congress (passed bill) is the product of that government's operation. Contributing to the operation of the Congress can never be a violation of such an oath.
Contrary to commonly held understanding, the Law is not a cut-and-dry thing. This is why courts of appeal exist in the first place: even the highest quality legislation, written by the most astute authors, will inevitably encounter circumstances unforseeable when it was written and passed that will force it into conflict with other laws, principles, or societal values - all of which also evolve.
As such, it is not subversive or contrary to participate in lawmaking that may seem contrary to existing laws. Rather, this is part of the normal operations of lawmaking, and when those conflicts/contradictions are made salient by circumstance, there are institutions which have been empowered to resolve them.
The entire body of court precedent is precisely this. But those decisions, when they were handed down, frequently acted in direct contravention of the will of Congress or the Executive. The Supreme Court wasn't in violation of the Constitution when it thwarted the efforts of the other branches. In the same way, the Congress, and even the Executive, are - by the Constitution's own design - free to (attempt to) thwart the will of the Supreme Court. The 'separation of powers' in 'distinct, co-equal branches of government' is an intentional feature of the U.S. Constitution and the design of the government's structure.
tl;dr - Passing such laws as are asked about by the OP are entirely within the bounds laid down in the Constitution, so participating in their passage is not a violation of one's Oath of Office.
So there are a few ways to "overrule" the supreme court. First, it's important to note that the supreme court does have Original Jurisdiction in some matters and those are not inherently asking constitutional questions. As such, a simple change to the law will to reflect the way the law should be interpreted would be sufficient to overturn their decision. The second way is for the passage of an amendment to the Constitution. The 13 Amendment to the U.S. Constitution outlawed slavery and moved the power to legislate further on slavery to Congress, so the states could not circumvent the Constitution ban. It also had the knock on effect of overturning all SCOTUS decisions that favored a pro-slavery position up until that point.
Finally, SCOTUS can and has overturned themselves. Brown v. Board of Ed effectively overturned their "separate but equal" ruling that kept Jim Crow laws enforce, and the definition of "Fighting Words" has been narrowed in all subsequent cases since SCOTUS first acknowledge the legal concept as a limit on Free Speech. Further more, the standards by which the government can limit free speech have tightened over multiple SCOTUS rulings from the "Clear and Present Danger" to the "Imminent Lawless Action" standard.
Your confusion likely arises from the following holding synopsis of the ruling, emphasis mine:
Held: The Constitution does not confer a right to abortion; Roe and Casey are overruled; and the authority to regulate abortion is returned to the people and their elected representatives. Pp. 8–79.
This is not a statement of constitutional requirement, but a reiteration of basic fact: if the constitution does not forbid regulation, then regulation may be enacted. All regulation is enacted through legislative authorities, or through agencies created through delegation of such authority. Such authorities are chosen by the people and derive their power from the people. It's just reiterating the default situation of (American) democracy. Moreover, even if it were some sort of precise and binding constitutional assertion, it nowhere specifies the power is handed to the States exclusively, and Congress is itself composed of the elected representatives of the people, and derives their power from the people.
Indeed, Kavanaugh's concurrence states
The Constitution is neutral and leaves the issue [of abortion] for the people and their elected representatives to resolve through the democratic process in the States or Congress—like the numerous other difficult questions of American social and economic policy that the Constitution does not address.
After today’s decision, the nine Members of this Court will no longer decide the basic legality of pre-viability abortion for all 330 million Americans. That issue will be resolved by the people and their representatives in the democratic process in the States or Congress.
Thus explicitly endorsing that Congress can still exercise control over the abortion issue using whichever powers the constitution grants to it that it can properly bring to bear against it.