Docker could do a lot better job in the packaging of their software. Even major updates require manual uninstalling and reinstalling it... Podman just works.
Docker could definitely do a much better job of making packaging easier. The docker-rootless just includes an sh script which has several of the files inline and writes them to the target location… assuming you're making a user-only installation (even though other potions of the setup require root intervention).
So packaging this requires reverse engineering how the installation process works, and extracting some of those inline files from the sh script, and figuring out where they'd be installed for a system-wide location.
> I cannot install it as nonroot user
You still need root privileges to install podman initially.