$ sudo unshare --mount
$ mount | grep '/ '
/dev/mapper/fedora-root on / type ext4 (rw,relatime,seclabel,data=ordered)
$ mkdir /media/tempns
$ mount /dev/mapper/fedora-root /media/tempns
$ ls /media/tempns
bin  boot  dev  etc  home  lib  lib64  lost+found  media  mnt  null  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
$ mount | grep root
/dev/mapper/fedora-root on / type ext4 (rw,relatime,seclabel,data=ordered)
/dev/mapper/fedora-root on /media/tempns type ext4 (rw,relatime,seclabel,data=ordered)


# Testing from another terminal:
$ ls /media/tempns/
$  
# No output, there is nothing in there.
$ mount | grep root
/dev/mapper/fedora-root on / type ext4 (rw,relatime,seclabel,data=ordered)