I've been wanting something like this that isn't artifactory (I've ran it in previous companies, it's not a great experience), so I had been thinking of doing it myself, but never bothered. One idea I had is to write a proxy that essentially translates the various package manager endpoints into OCI registry, thus causing everything to be stored on any OCI backend. My thinking was this way you could in theory use any OCI backend (including ready available, battle-tested self-hosted applications), but this proxy would never need it's own state, thus making it (hopefully) easier to run.

Now that you've implemented, was there a reason you didn't go for such an approach so that you would worry about less as someone hosting something like this?