Some interesting things to note here:
1. No one is using many of these objects in the same way, though sometimes they sort of kind of work together anyways.
2. No one I've looked at so far implements parts of the spec that I'd consider "interesting but unusual." Things like following non-actors. I suspect the vast majority of them would break if you tried
3. Mastodon's made several decisions that are between odd (using summaries for CWs) and outright ignoring parts of the spec