Le Pen yes, Trump I'm really not sure at this point but that's neither here nor there.
But for the reasons you stated, and more besides, support for Ukraine is unlikely to end unless a bunch of people in the West end up being very dumb. And so long as Ukraine gets good-quality armaments, training for it, and financial support too keep a war effort going, Putin can throw as many of his poorly trained mobiks in old ass tanks and pickup trucks as he wants at them. All he'll probably do is provide more effective advertisement for NATO arms while killing more young males in a country that is already lacking in them, tanking their economy even further as the only comparable advantage Russia has anymore is selling cheap gas to China and India, and shoot their demographic pyramid in the head while they're at it.
Putin can perhaps in the long run ruin Ukraine, by also ruining Russia maybe slightly less. If that's the plan, well, I can't exactly stop him but that would be a product of spiteful stupidity far more than ruthless pragmatism.