Ah maybe a significant advantage of incus is it doesn't require sudo. I remember that also being required for nspawn.
https://github.com/systemd/systemd/issues/30239 https://github.com/systemd/systemd/pull/26826/files
systemd-nspawn may be invoked with or without privileges. The full functionality is currently only available when invoked with privileges. When invoked without privileges, various limitations apply, including, but not limited to