Conducting polls is costly, so I don't see why anyone would spend money outside the US to find out public opinion on a fairly obscure US politico-legal matter... (as opposed to opinions about Trump's foreign policy, which does get polled, see the Pew survey in the other answer.) The best you can probably hope for is some foreign media roundup which often end up asking some local expert[s] on their opinion...
there was little immediate international reaction to Trump's impeachment for a U.S. leader who has already upended the U.S.'s relationship with much of the world by casting doubt on longstanding alliances from the G-7 to NATO, pulled out of global climate and nuclear accords and generally treated foes like friends, and vice versa.
On the day of the vote, Iran's state media noted it was happening and that the debate was sharply drawn along politically partisan lines, but has not commented since. [...]
There was no official mention of it in North Korea or China, where state media often look for opportunities to bash American officials and leaders. However, the Hong Kong-based South China Morning Post noted Beijing officials may be concerned impeachment will be a distraction from Trump's China trade talks. [...]
"Brazil is deeply polarized and seized with the daily dramas of their own president," said Robert Muggah, co-founder of the Igarapé Institute, a Brazil-based think tank. "A majority of Brazilians shrug their shoulders when asked about Trump's impeachment." [...]
There was also no word from Saudi Arabia, where the government is close to Trump. [...]
There were few media hot takes out of India or South Korea or other places where Trump is closely watched. Most newspapers from Mexico to Spain ran straightforward news stories on the vote.
Peter Bayer, a German politician who is a close associate of German Chancellor Angela Merkel and a member of her ruling Christian Democratic Union party, said that Germans have been closely watching the impeachment proceedings in Washington.
"The U.S. is our most important friend and ally outside Europe," he said.
But Michael Wohlgemuth, a German-born expert on European political affairs at the Foundation for Economic Governance and Public Law in nearby Lichtenstein, said he believes most Germans will be happy to see Trump impeached.
"Trump is most unpopular in Germany. Only 10% of Germans trust the American president – compared to 35% who actually trust (Russia's) Vladimir Putin. This is no expression of engrained anti-Americanism, but a most damning verdict on the person himself. After all, 86% of Germans used to trust in the leadership of President Obama."
In Moscow, President Putin briefly touched on Trump's impeachment during his annual marathon end-of-year news conference, saying that the impeachment was far-fetched and "just the continuation of the domestic political strife." Putin predicted that the Senate would reject it. Russia's leader has previously made similar remarks.
One place where Trump's impeachment could be expected to resonate strongly is Israel, where Prime Minister Benjamin Netanyahu is fighting his own battle for political survival after two inconclusive elections and indictment for bribery, fraud and breach of trust.
Gilead Sher, previously chief of staff in former Israeli Prime Minister Ehud Barak's government, said that Trump's impeachment and Netanyahu's indictment "reflect both societies' rejection of moral turpitude and solidify the rule of law."