New comment by paper42 on void-packages repository

https://github.com/void-linux/void-packages/issues/35410#issuecomment-1085207003

Comment:
> Yet when I run
> ./xbps-src pkg
> I get errors on namespace.

xbps-src creates a directory with a minimal void system, the state of this system is defined (more or less) by HEAD. The package is then built in this "container" which uses namespaces, so you can't run that nested inside another container without taking extra steps (if that's possible).
Alternatively, you can use the ethereal chroot style which uses symlinks to emulate a chroot without actually changing the root, but this destroys the container. For documentation on this, see common/chroot-style/ethereal.sh and the way CI is set up that was already linked before.

@Anachron missed the point of this issue, please ignore that comment