Submit a bug report to Steam.

I'm guessing you forgot to add DRM kernel mode setting. What you need to do is create /etc/modprobe.d/nvidia.conf, and add

options		nvidia_drm	modeset=1
blacklist	nouveau

then edit /etc/mkinitcpio.conf to have

MODULES=(nvidia nvidia_modeset nvidia_uvm nvidia_drm)

and ensure /etc/mkinitcpio.conf also has the modconf hook

HOOKS=(... modconf ...)

then run mkinitcpio -P, restart, and enjoy Wayland.

Source-available is not open source. Open source means you are granted the right to modify the code and distribute that modified code as your own project, with some or no restrictions, depending on the original projects license. This license only grants the access to compile and distribute the original unmodified source code.

The fact that this license doesn't grant modification rights makes this about as open source as Unreal Engine... which means it isn't.

I don't think this is a bad project, but advertising it as open source is a lie. It's source-available shareware.