Found some time to look into the missing static os-release information in #FreeBSD OCI images and submitted a fix:
https://github.com/freebsd/freebsd-src/pull/2467
Example output:
$ podman images
REPOSITORY TAG IMAGE ID CREATED SIZE
localhost/freebsd-runtime 15.1-RELEASE-p4-amd64 3dea688d38ab 40 minutes ago 34.1 MB
$ podman run --rm 3dea688d38ab cat /etc/os-release | grep '^ID=' | cut -d'=' -f2
freebsd
