@trwnh Fedify does run well behind a reverse proxy, and it doesn't actually require a fixed base URL—it can derive the base URL from the incoming request. Ghost takes advantage of exactly this to implement virtual hosting on top of Fedify, so in principle the kind of per-actor custom domain you're describing should already be achievable without changes to Fedify itself.

@hongminhee i think the only support from fedify needed is basically like an environment variable or property for wherever identifiers are assigned or dereferenced

so for example if the service is mastodon.social it would assign identifiers using trwnh.com/mastodon/ as a base uri

it only needs to know which uris are already used, so it doesn't assign an id that's already in use.