Not counting the Steam Deck, since KDE isn't actually turned on while you're running games.
Normally I'm a Gnome guy, but I'm building a tiny low power portable computer and wanting to keep resource utilization low, so I'm investigating other options.
Sway mixed with KDE,
games don't really like it and Pipewire doesn't work for video recording for some reason (it has to do with the KDE xdg-desktop-portal) but it's a small price to pay for salvation I guess.
I know Sway is a window manager, not a DE - but KDE applications and services seem to fill the gaps.
They're not necessary, but you won't catch me dead with a GTK file chooser popup open, and I haven't figured out how to set up Ranger to replace Dolphin (nor do I really want to).