/usr/bin/s390x-linux-gnu-gnat is in gnat-7-s390x-linux-gnu 7.3.0-16ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/s390x-linux-gnu-gnat-7
/usr/bin/s390x-linux-gnu-gnat-7