I will say that, as someone with more experience on Fedi than Nostr, that it isn't uncommon at all to run into reply threads where you can't see half of the participants because of your instance's defed list, so us being able to see these users at all is a step up in that regard, but I do agree that some kind of visual indicator to differentiate ActivityPub users that can interact with us from ones who can't would be a really good idea.
