Putting aside your implied definition of Leftists here.
The Palestinian point is broadly enlightening, but maybe not in the way you intended.
Armed struggle for the purpose of self determination should be materially supported in Ukraine, but not in Palestine.
This is the glowing contradiction, and I'm not sure real leftists are the most guilty party here.
As someone who considers themselves on the left, i have broadly the same view.
I also don't have a hard view on gun control, because if the state authorities are militarised then it's hard to argue that civil society can't be.
The solution for this of course is to demilitarise the police.