I want something much simpler anyway. But I don't want to use JSON-LD, so no direct interop will be possible.
It's hard to find a developer who wants to use JSON-LD in a social application. But the good news is that JSON-LD is not required, and not even used: our servers produce and consume plain JSON documents. Yes, these documents have @context property, but for most implementations this is purely ceremonial thing.
Here's some test data: https://funfedi.dev/support_tables/hashtag_jsonld/
That's what I meant when I said that the flavor of ActivityPub we use in Fediverse is already quite close to 'Really Simple ActivityPub'. Nobody wanted an over-engineered protocol, so it was simplified and optimized by early adopters.