The current EU assessment is that they might try and annex some of these countries before NATO can respond, hoping to present them with a fait accompli in the b

The current EU assessment is that they might try and annex some of these countries before NATO can respond, hoping to present them with a fait accompli in the belief NATO and the US and EU's lack of willingness to go to war with Russia will stop them from responding. So yes, this is an actual feat.