As of writing, none of the 2020 Democratic candidates have expressed support for a public option with $0 copays/$0 deductibles.
- Prefer Medicare for All/single payer instead of a public option.
- Have released plans to lower copays/deductibles, but do not say they will be $0.
- Do not mention copays/deductibles at all, instead focusing elsewhere to reduce cost.
Details about Biden, Buttigieg, and Yang can be found in @Carduus's excellent answer. The rest of the candidates are below:
Michael Bennet introduced the Medicare-X Choice Act of 2019, which seeks to reduce costs through a reinsurance program and by expanding tax subsidies, also capping premiums at 13% of an individual's income.
Michael Bloomberg wants to lower general health care costs by capping drug prices and capping how much doctors/hospitals can charge out-of-network patients. His public plan would be free for low-income people in states that did not expand Medicaid under the ACA.
John Delaney's BetterCare proposal seeks to decouple insurance from employment by automatically enrolling people into a government health plan. Those people can opt-out of enrollment and instead receive a tax credit to buy private insurance.
Amy Klobuchar wants to to lower copays/deductibles by increasing ACA subsidies and providing cost-sharing reductions. In addition, she has co-sponsored the State Public Option Act, which states it will:
(A) impose premiums, deductibles, cost-sharing, or other similar charges that are actuarially fair[.]
Deval Patrick is scheduled to release a healthcare proposal sometime this month. As of today (Jan 15th, 2020), it has not been released. However, his site claims it will create a public option "that is free to some and low cost to others".
Tom Steyer wants to lower costs by renegotiating payment rates to providers, expanding ACA subsidies, and requiring all doctors to accept the same insurance as the in-network hospitals they work at.
Elizabeth Warren supports creating a public option within her first 100 days, then over time transitioning to the Medicare for All Act of 2017. However, I've found no evidence that her public option and $0 copays/$0 deductibles will happen at the same time.
Gabbard co-sponsored the Medicare for All Act of 2019, which has the same language as the Sanders bill, but without the exceptions. Her official platform states 'I support a single-payer system that will allow individuals to access private insurance if they choose.' She says there is a 'role for private insurance', making reference to Canada's system (a government run program supplemented by optional private insurance). She has made some statements in interviews saying she favors consumer choice and allowing people to keep their current insurance if they wish.
While the candidates all express a desire to lower health care costs, the ones who support a public option don't seem to focus on copays/deductibles specifically (and many don't even mention them). Instead, they primarily focus on lowering prescription drug prices, premiums, or general "health care costs".
When a candidate does mention copays/deductibles, they say they will lower them, but do not specifically say they will be $0. Klobuchar seems to be speaking the most about deductibles (at least in what I have found), but again, only lowering them, not making them zero.