Strfry is doing pretty good without any mods. It can be used as a relentless database of notes, and any other custom logic required can be done in a proxy.

Take nip42 auth for example. You go down the rabbit hole of this nip, which is fairly solid, and realize there are a bunch of ways you could potentially use it. So many ways in fact that it becomes really hard to design a flexible solution built into the relay itself. (And this is why it has not been implemented in strfry).

Using a proxy to prototype is a good first step. Then if clients can gather some consensus on how they want to do something, it will be more clear what to write.