To begin with, the case you raise is quite improbable, and the consequences you foresee, too. Adopting Bitcoin fully would not solve Russia's problems as you have been told, but if Putin were to take a position like Bukele, Europe and the US would not ban Bitcoin as it would be shooting themselves in the foot. All this taking into account that apart from Bitcoin the adoption by some governments has already started. There is a list in the following thread:
Governments that accept Bitcoin for public services.Some of those listed are local governments, but that's a start.
It is 100% quite improbable. I wouldn't say impossible neither because technically speaking it is not impossible, but when most of them already regulated it in a way that would make it quite legal and lawful to use and trade, it would be unwise to turn that all around and do something totally different on the opposite direction. Sure Russia deal with crypto is a bit bad for the nations that put sanctions, they would prefer if Russia got out of crypto, but they won't get out of crypto just because Russians got in.
Plus, it is a bit about putting a political stance to put sanctions and not some economical approach since they would probably keep working with them anyway.