@thomas-k8s Nah, you lose the native XMir windowing with that. I'm more partial to how we did it in the days before libertine's release back in 15.04 (still chroot, not libertine's proot which seems more restrictive, but using XMir with matchbox-window-manager to provide some semblance of window managment)
Nowadays, I'm looking into something similar, but using the Gentoo Prefix in place of the chroot, so it runs unprivileged. Obviously will generate a LOT of I/O so if anyone else goes this way, I highly recommend running the bootstrap as far as it will let you using an NFS root mounted into the home directory somewhere (mine is .local/system) and then copy it to device and finish the bootstrap using an NFS-mounted TMPDIR (because bootstrap will only let you go so far before portage tells you that it needs root permissions for some reason when bootstrapping straight to an NFS shared folder)