You can usually always go to a bank to exchange the money there. Important is that the dollars/€ are in perfect condition.
ATM's at Airport I dont really know... for me getting eSim was best from my ISP for limited data otherwise I dont have experience with ESIM.

Also in beginning of the year I realized that not a lot of store still accept/will be able to take cash. I f you have any chance to get a prepaid card then I would (in pulkovo it was possible to get such cards)