Here is someone trying to fix the issue who is also posting a pr to UnrealEngine on github Updating UE5 to work on Wayland. I got it working, sort of, mostly. Swapchain issues.
Here is the post I previously mentioned covering this with some potential fixes (though I think its all SDL3 and Wayland as the focus fixes for KDE Plasma do nothing if not started with SDL_VIDEODRIVER=x11) Unreal Editor 5.7 UI interaction is broken on Linux for ~3 month already
Here is is a post covering the focus fixes, but again they did nothing for me without the x11 driver for sdl3 Unreal Editor 5.7 UI interaction is broken on Linux for ~3 month already - #61 by _st_Mr.Deady4