I did not found an explanation so far how I could do IPv6 with podman.
In /etc/cni/net.d there is a file I can change - but putting IPv6 stuff in there did not work.
Metadata Update from @otaylor: - Issue status updated to: Closed (was: Open)
https://github.com/containers/libpod/issues would be better.
https://blog.42.be/2019/03/routable-ipv6-containers-with-podman.html
looks relevant.
Thanks!