Pole here. $60k/yr is a slighly above average salary for a senior backend engineer in Poland so I think you're looking too far. It's much easier to find an even better offer from DACH countries.

I know people from Poland who work remotely for the US. Even though salary is much better ($120k is a starter), you need to assume you will be expected to participate in late night meetings, on-calls and in general assume much worse work-life balance than we, in Europe, are used to.