podman/docs/source/markdown/options/gidmap.container.md

--gidmap=container_gid:host_gid:amount

Run the container in a new user namespace using the supplied GID mapping. This option conflicts with the --userns and --subgidname options. This option provides a way to map host GIDs to container GIDs in the same way as --uidmap maps host UIDs to container UIDs. For details see --uidmap.

Note: the --gidmap flag cannot be called in conjunction with the --pod flag as a gidmap cannot be set on the container level when in a pod.