Package:Fchroot

root # cat >> /etc/portage/package.use << "EOF"
app-emulation/qemu static-user qemu_user_targets_aarch64 qemu_user_targets_riscv64 qemu_user_targets_arm
dev-libs/glib static-libs
dev-libs/libpcre static-libs
sys-apps/attr static-libs
EOF
root # emerge -av fchroot

add sandboxing to the raspberry pi make.conf

   /mnt/funtoo/etc/portage/make.conf - add sandbox

FEATURES="-pid-sandbox"