Iām not super a fan of using json. I feel we could still use text as the medium. Maybe a modified version to fix any weakness.
What if instead of signing each twt individually we generated a merkle tree using the twt hashes? Then a signature of the root hash. This would ensure the full stream of twts are intact with a minimal overhead. With the added bonus of helping clients identify missing twts when syncing/gossiping.
Have two endpoints. One as the webfinger to link profile details and avatar like you posted. And the signature for the merkleroot twt. And the other a pageable stream of twts. Or individual twts/merkle branch to incrementally access twt feeds.