The emoji reactions are cool but isn't "likes" only being federated by the origin server, an ActivityPub thing?🤔
If I like this post, you see, that I liked it and all others who see this post see it also but only you get notified about it. Federation itself means more, that comments are shared across instances. But often when you jump in a conversation not all of them are federated because not all people follow each others and here comes the point where not all comments are federated and you have to view that on the original instance. Same as if I would only anser you and untag the others.
About the Meta thing, there was some days ago an article about how to make money in the future social web ... it is more likely they will use a modified version of the AP protocol to ask for money for lets call it premium features.