It should be noted that Wayland has a variation called xWayland, which blends parts of xorg server in with Wayland, and ive personally made custom resolutions through the xorg server that will apply with Wayland.
Heres that aforementioned variation: nixpkgs/pkgs/servers/x11/xorg/xwayland.nix at 31ac92f9628682b294026f0860e14587a09ffb4b · NixOS/nixpkgs · GitHub
Heres my nixos config, running an RTX 3080:
################################################
### ###
### WINDOW MANAGER SETTINGS/WAYLAND/X11 ###
### ###
################################################
services.xserver.enable = true;
services.displayManager.sddm.autoNumlock = true;
services.displayManager.sddm.enable = true;
services.displayManager.sddm.wayland.enable = true;
services.desktopManager.plasma6.enable = true;
services.displayManager.defaultSession = "plasma";
services.displayManager.autoLogin.user = "jason";
hardware.opengl = {
enable = true;
extraPackages = with pkgs; [libvdpau-va-gl];
};
services.xserver.videoDrivers = ["nvidia"];
It may be worth giving it a whirl to see if this solves your problem. I also dont like gamescope as it really messes with my muscle memory.