A BUG in SDDM recently prevented Wayland form starting, Version 0.21.0.36_6 contains the Fix.
Note that you need NVidia-DRM in operation to run WAYLAND.
You also need pkg Seatd installaeed as described in Handbook chapter 6.
On Freebsd 15.1 you need KMods ( drm-612-kmod & nvidia-drm-612-kmod ) with version at 150100 or above
You can not use old kmods with version 1500068 as they are for FreeBSD 15.0 an probably cause a kernel panic if used with FreeBSD 15.1
This is what you want. note: the highlighted version number
150102
$ pkg info | egrep "nvidia|drm|sddm "
linux-nvidia-libs-595.99.02 NVIDIA graphics libraries and programs (Linux)
nvidia-driver-595.99.02 NVIDIA graphics driver userland
nvidia-drm-612-kmod-595.99.02.
1501502 NVIDIA DRM Kernel Module
nvidia-drm-kmod-595.99.02 NVIDIA DRM kernel module
nvidia-kmod-595.99.02.
1501502 NVIDIA graphics driver kernel module
nvidia-settings-595.99.02 Display Control Panel for NVIDIA graphics
sddm-0.21.0.36_6 QML based login manager
You can achive this by building the packages from a fresh /usr/ports tree that you fetch following the instructions in the handbook chapter 4.5
https://docs.freebsd.org/en/books/handbook/ports/#ports-using
You can not use the ports distribution on the 15.1 Relese media as that ports tree is form the month of May 2026 and does not include
the Versions of software you need.
//Regards