You do need the blocs for smaller countries. Imagine if Delaware had to go on its own completely.
Yes, scale matters. However, a sovereign nation cam make all sorts of ‘deals’ with other sovereign nations, without unduly sacrificing sovereignty. NATO, and USMCA are examples. The EU was fine, when it was content to be the European Common Market.
The USA, (and Canada, and Australia) are unions of otherwise sovereign states. These federal nations differ from the EU, in that they don’t have the extreme ‘democratic deficit’ that the EU has.
Britain and Poland can find all sorts of things to join forces, collaborate, or cooperate over — they don’t need to compromise their core beliefs, or cultural essence to do so.