yrro@host$ podman run --rm -it debian:unstable bash -x -c 'id; cat /proc/self/uid_map'
    + id
    uid=0(root) gid=0(root) groups=0(root)
    + cat /proc/self/uid_map
             0  876099160          1
             1     231073      65536

This is done as a regular user with special rights on the system; all that is required are entries for yrro within /etc/subuid and /etc/subgid. There's no equivalent of Docker's daemon that hands out root on the machine to anyone who can connect to its socket.