OK. I think you analysis is more-or-less on the mark. Putin definitely felt emboldened because of the weakening bonds among the western nations, thanks to Trump. That is for sure. The obstructionism in Congress by a minority (Republicans) to send weapons to Ukraine likely helped Putin's decision. And, if we care to go back, the lackluster response from the west (and Obama) to the seizure of Crimea certainly didn't help. That harkens back to the seizure of the Sudetenland, which was met with lots of bluster but no action. Same with Crimea. In both cases, the aggressor leaders were correct in their assessment of western resolve (i.e. there was none).

Putin probably overplayed his hand with Ukraine. Maybe he was thinking it would be like seizing Austria in 1936 (i.e. no declaration of war followed, and resistance was token, at best). Instead of a cake-walk, he faces stiff resistance, lots of western aid, sanctions, and a lot of coffins. Ironically, the Reps are responsible for his recent gains because they thought of Ukraine aid as a bargaining chip (at best), without regard to the geopolitical consequences, and played games. Result: Ukraine couldn't hold some of their forward lines anymore and had to fall back until more materiel was received.

As a bonus, the US has accepted several hundred thousand refugees from Russia and Ukraine since the initial invasion. Contrary to what border hawks want, Putin is fueling more refugee/asylum requests in the US. And, as you say, it all stems from Rep and Trumpian actions.