[...]
Hm, then the option would be to stay on OMV4
Looks like I will just do that for my RPi installations for the foreseeable future. I recently tried to migrate an OMV4 installation to OMV5 (using #38) and that didn't work as expected. Luckily it was a working clone of a VM. And just for experimenting, I already have two OMV5 VMs (one more or less standard, the other with Proxmox). I can find my way around in Portainer, but just kicking off an image in the old Docker GUI is still a lot easier, all settings for a container are on one page instead of switching between tabs with the tab buttons somewhere half way down the page instead of near the top where they can stick in a fixed position.