Gonna go against the grain here a little bit, but why? If they are federated, it will mean that you can move off of threads more easily to other servers and not get locked into a walled garden. Encouraging companies to embrace federation will avoid the shit shows like we've seen at twitter and reddit, since users will be easily able to jump ship without much loss. Additionally, apps like threads make federated platforms much more approachable to newcomers and those who do not even know what the fediverse is.

I'd love someone to explain it to me, but this feels like a massive footgun.

That sucks and seems pretty short sighted :/

Does this mean posts from beehaw will not be in my lemmy feed, or is it simply I cannot interact with those posts in such a way that beehaw users would see?

Are other lemmy instances not federated with beehaw?

Nope, its free and oss. It's in beta rn though so it has to be installed through testflight. They have a channel over on lemmy.ml https://lemmy.ml/c/mlemapp.

Only on iOS, but afaik there are a few options on android atm.

Went ahead and subbed on patreon. Hope that lemmy survives the growing pains and can develop some of the community that reddit had!

Also if there are any fellow former apollo users would def recommend checking out Mlem, its in testflight right now but seems to be working towards the experience that apollo gave on reddit.