What can be used to detect impurities at those level? Maybe there is an additional machine needed that can also be built in a garage.

Maybe check how long it is already going, so it can give you some confidence. Forgejo is a fork of gitea, which is a fork of gogs.

Also, codeberg, a nonprofit from Germany, is supporting development.

https://docs.codeberg.org/getting-started/what-is-codeberg/

The codebase history of Forgejo and its predecessors predates Codeberg. However, since 2022, Codeberg is backing the development of Forgejo as an umbrella organization.

Can you elaborate on this?

I am looking into doing the same as op and I have no idea what I’m doing.

If you have been running servers since the 90s, can you provide the list of do and donts?

Did that instance have public registration? What speaks against having it for private (family) use only, as a gateway to the public instances?