On my x86_64-linux system running the Guix system, when I include gdm-service in my system services, 'herd stop xorg-server' results in a state where I seemingly cannot recover except by rebooting. I'm left in what appears to be an empty Linux text console with a cursor in the top left corner, but the keyboard is unresponsive, and I'm not able to switch VTs. Perhaps there is some SysRq key combination that could be used to recover, but I haven't yet tried.
Since I prefer to use Wayland, and would rather not have a separate Xorg session running that I never use, this means that currently I must avoid using 'gdm-service' entirely. Note that this is on a system running fairly recent 'master', but before 'staging' was merged. I'll try again and report back after I've finished rebuilding my post-staging-merge system. Regards, Mark