Can we get more decentralised than the Fediverse?

Pull not being a good model of two way communications is going to be the major blocker here in my opinion. It's going to mean that people are only going to see comments and reactions on their posts or comments from people they already subscribe to, because their RSS reader would have no possible way of knowing if anyone outside of that list commented, since you can't get notified of content sources you don't already know about, only poll ones you already know. That's already bad enough (one of the big negative things people with large followings on the fediverse talk about is how they can't see what people are saying in the replies to their posts a lot of the time if the servers those people are on are blocked by their server, which means hate and harassment and one sided conversations can fester, and often many commenters can't even see each others' comments, leading to people saying the same things over and over exhaustingly). This also means that people who don't have any followers will literally be essentially muted by default: no one will see their comments or interactions, because no one polls their feed yet, which means that it's basically pointless for them to interact at all, which sounds dispiriting and would probably lead to no one wanting to use this type of social media — moreover, it also creates a catch-22 problem, because a major way to get followers in the first place is to directly interact with other people and bigger blog posts, to make people aware of you and maybe get some of them interested in hearing more of what you have to say, yet in this model, you can't really interact until you have a following already, so your main means of getting a following is gated behind needing a following to work!

I agree that pull is the best model for posts. For comments I still think the best model is to push them to the post author, and let the post author moderate. This way people who can behave civilly can get an initial audience by writing comments, and having a link to their blog in the profile, with no intermediaries involved. If someone doesn't like the moderation, they're always free to write a comment-as-post, where they can write anything they want but have to take care of distribution themselves.

the thing is, with no intermediaries involved, more specifically, without any proper "search engines" (or "aggregators") involved, the network will suffer greatly from a content discovery problem regardless (as the fediverse currently is, IMO).

with presence of such services, the problem of comments (and reactions in general) can be solved too. if a poster is ok with engaging with potentially hostile content, then they can get reactions to their posts from aggregators that aren't heavy handed on moderation. if they don't want to bother with such interactions, then they can choose safer aggregators. if they want, they can only pull reactions from feeds they are already subscribed to, similar to private posts on twitter.