Ah, fair enough, I see the use of namespaces now. I thought that would be exclusive to buildFHSUserEnvBubblewrap or whatever that was called.
I still have not actually tried it, but when I looked into this for another tool it seemed like it had equivalents for most things you need to create a useful chroot. It seems that there’s at least a bind mount hack through fuse: https://bindfs.org/
It would be interesting to see if a Mac OS implementation is feasible, even if not fully featured. In my mind chroot provides most of what you need for this, even if proper Linux namespaces are much nicer to use.
Not that I have the hardware to try myself, or much personal interest in non-Linux support. But I don’t think it’s entirely infeasible if there’s demand.