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.
Take a look at Hyprland, they have an xdg-desktop-portal implementation that apparently works with that stuff. https://github.com/hyprwm/xdg-desktop-portal-hyprland https://www.hyprland.org/