While I can't test, as I don't have a CONFIG_VT=0 kernel, the problem is that while all TTYs are on seat0, not all seat0s have TTYs
it seems to use TTYs if it's seat0
However with systemd something like sd_seat_can_tty()
can be used instead.
However changing it seems a little odd here compared to changing it in wlroots and weston, it seems that the library is being 'manually' loaded....