> Yes indeed, I should've expanded to requiring user namespaces and other kernel magic I can't expect from any random box i wanna work on.

That's fair, do have to make sure to avoid to modules that do user systemd services.

Longer term, though, I am hoping https://github.com/InitWare/InitWare will help with the userland part. And I hope to personally help with things like

https://lists.freebsd.org/archives/freebsd-arch/2022-January...

https://lore.kernel.org/lkml/f8457e20-c3cc-6e56-96a4-3090d7d...

to get us more sane cross-platform system calls.