Makes a lot of sense.

In the end, though, I feel like committing to a pandoc for fediverse platforms would be a better effort if every platform is going to have to cook up some fall back that works everywhere.

With a pandoc equivalent, you get a buffer between how a platform wants to manage its content structure and the translations that have to bridge differences between the platforms. That way a shared project should be viable where, so long as each translation is reasonable, no platform should be upset. I don’t know how easy it is to tell what platform content comes from in the protocol though.