Two good points here OP. Type docker image ls
to see all the images you currently have locally - you’ll possibly be surprised how many. All the ones tagged <none>
are old versions.
If you’re already using github, it includes an package repository you could push retagged images to, or for more self-hosty, a local instance of Forgejo would be a good option.
There’s lots of ways to skin this particular cat. My current approach is low powered Synology (j series?) for mass storage, then 1 litre PC’s running proxmox for my compute power using their NVME for storage, all backed up to the Synology.