About 10 months ago I posted this thread saying that it would be useful for the fediverse to consider post once, share everywhere paradigms: https://lemmy.ml/post/641509
And now we have The Verge writers saying similar things: https://www.theverge.com/2023/10/23/23928550/posse-posting-activitypub-standard-twitter-tumblr-mastodon
Maybe worth re-considering.
I’m not sure I understand how this isn’t already possible. Create an account on some federated platform, such as your own self hosted one, and people from any federated platform can now follow you. Isn’t that already POSSE?