Re. client side prediction and server reconciliation, may I recommend https://gabrielgambetta.com/client-server-game-architecture....? Even if you don't roll your own solution, it might be worth understanding the theory so you can use these libraries correctly.
I properly animated a model with blender, and am able to move the parts I want accordingly. It was not easy but I made it.
I also managed to implement the recoil algorithm I want.
I modeled guns.
I will probably struggle to implement server reconciliation to mitigate lag, I found 2 modules that does it, one in C++, one in gdscript.
Obviously the gdscript one is slower, but it's hard to know how much slower, since obviously a game like counter strike is very fast paced.
I also want to implement a panini/wide angle camera, also found a module for it.
Moving slow with bad mental health and anxiety, but having fun.