The Polish armed forces are training citizen volunteers how to be armed partisans, firing rifles and donning gas masks.
That’s… not great. The program is apparently popular, so they are expanding its capacity so that every adult male receives the training.
Probably couldn’t trust Trump to come through, but you have to keep in mind that he’s not an autocrat quite yet. Not everyone in the US government shares his views on NATO and the commitments the US has pledged to under that alliance. Look at the rest of NATO. You have four of the top ten military powers in the world to start off with (UK, France, Turkey, Italy). Then add to that the rest of Europe and Poland’s own considerable military might. Canada would also join in, and those otherwise peaceful Canadians go fucking nuts when provoked. Even disregarding NATO, you have the Anglo-Polish Alliance, which is a mutual assurance that the UK provides military assistance (or vice versa) if their ally is invaded. Poland also has many close friends and allies in the old East Bloc, so the misconception that they would be left to their own devices is simply untrue.