As a lot of reviewers are saying, it feels very close to the Steam Deck controls. The trackpads are slightly different texture and a bit more refined (in a good way). The D-pad and face buttons feel good to me as a longtime gamer.
I’m used to the Xbox Elite 2 these days and this is quite a bit lighter in weight and feels more like plastic, but still solid enough (again, like the Deck). I do maybe prefer the 8-edged D-pad and I’ll probably miss the trigger stops, but gyro and trackpads and grip sense should more than make up for it.
Seen your post, and my DE is also KDE plasma. I’m not 100% sure if I have the same issue with the pointer (easy to blame it on the game after all) but I’ve been able to do a test reboot with it plugged in and not have the issues I mentioned. That said I have not tried to do anything with grub so I have no data to contribute there.