I found a bug with nspawn that it can't bind mount while being in the mode which lets you delegate namespaces or whatever
Aka
If you have some kind of mount that matters like NVIDIA, you can't also create containers from containers.
So I just switched to LXC but I guess I should submit a slop PR as well. But yeah I guess Id just caution anyone who was going to use it lol
Nspawn has a lot of issues with bind mounts in general. They've never been fixed because pottery doesn't see the point. See for example: https://github.com/systemd/systemd/issues/26897