As others said, you'll get by with just speaking English - if you're serious think of what would matter aside from language: a life in Italy will be very different than a life in German, not only the weather but also the work culture. Also think of which countries 'match' your education, being somewhere with loads of jobs in your expertise will make things a lot easier. I'd advise anyone able to move from US to Europe to take a leap of faith - if it doesn't work out and the US has by then returned to normal you can just move back and if it doesn't work out and america didn't return to normal you'll likely be happy at least you got out before it got real bad.

Almost anywhere in Europe is the answer. My son did his masters in Denmark and never learned Danish. He lives in Germany now and speaks fuck all German.

Once in the Netherlands, after losing my glasses I asked an optician if he could speak English and he was thoroughly insulted.

Britain and Ireland are both native English.

in research? English is enough in most countries I think, I have friends here (France) who just start learning french after 10 years living here 😅 they just didn't need it before

If you're willing to learn at any pace, and can do at least some "skilled work" as they call it, then just about everywhere. Usually you have 5 to 10 years to learn the language if you want to stay permanently. You can get by with English in most of europe.
Usually, if there is not a lot of jobs you can do speaking English, it means that the region isn't exactly rich and/or accommodating anyway.

You'll get by just fine everywhere on english, but it'll be hard to integrate and make local friends without learning the language