Not the OP but Gnome does not support variable refresh rate.

I haven't looked at the link you sent but you should not have any issues as Linux is a kernel.

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/

You don’t need wine installed for Proton to work. Make sure you have the correct Vulkan drivers installed.

Do you possibly have two monitors? If so, Wayland is better for multiple monitors and different refresh rates.