@feditips So sorry to necro a super old post, but this is to top search result for how edit notifications work on Mastodon and I just want to clarify that "You can edit any post you've made, and it will send a notification to people who have already interacted with it to prevent any hijinks or shenanigans." is incorrect.
When posts are edited, ONLY PEOPLE WHO BOOSTED A POST ARE NOTIFIED. Other intractions such as favoriting and replying do not seem to trigger a notification, at least on stock Mastodon v4.2.1.