I've been using mastodon for nearly a decade now. The major thing I think is missing from ActivityPub is a decentralized/federated way of doing auth. The ideal for me in ActivityPub is having a profile/DID service provider that you then can attach to services. This would theoretically be like having just a federated identity (or however many identities you want) that you can then go to a lemmy instance or mastodon instance etc and "log in with federated ID" like log in with Google but not dependent on a corporation.
Auth and identity in general is definitely the biggest hurdle with ActivityPub. Right now it's a bunch of distinct and non-tied profiles, which isn't necessarily bad, but many people would like an easier way of doing this. Instead of saying "which lemmy do I want to join" it's just "which identity service do I want?" and then go to and use any mastodon or lemmy or Pixelfed service with that single account. There's many ways to do this, but it's definitely possible (in theory, right now there isn't a spec for this afaik, we just have DIDs and those are very very very young specs.
I'm just doing a bit of research (I'm also not the guy you were replying to :p), but I found the developer is really just one person seemingly (the only registered person I could find for the company representing Revolt [based in the UK]) and that is Pawel Makles. He's also listed as the data controller of all of your data https://revolt.chat/legal/privacy
My concern at first glance is this guy is only 21 years old (born 2003). I don't think the dev seems too shady from this quick look, but being only 21 with a bunch of private data doesn't seem too stable imo.