I don’t really know the details of how they would translate from app to app, but I do know that ActivityPub is specifically designed to allow all of its apps to pull the same information. If an app utilizes ActivityPub, it inherently has the capability of displaying all of its components.
If anyone sees that I’m wrong on something here, please feel free to correct me.
Lemmy is so much better than Reddit! Anyway, the admins of this instance are deciding what you’re allowed to see, just like Reddit.