

If I remember right, no. If I clean boot, load sddm, immediately type my password and log in, then I have to wait a while for the mouse to start working.
But if I clean boot, load sddm, wait the same 5-10 seconds, then the mouse starts working on the login screen and then just continues to work once logged in.
Hey, thanks for your comment! Someone on Reddit was able to help out, I posted the solution in the OP.