This somehow seems to be a solution in search of a problem. The reason people use self texting is that they _don't_ want to use another app. Not because the existing apps are somehow missing features. > I often defaulted to dumping notes into chat apps like Slack or iMessage What makes you think people think differently about this app? If people wanted all these features they would already all be covered by Apple Not…
What might be useful, if done well, would be adding tags to messaging similar to GMail's use of tags in lieu of folders, as a way of grouping related messages (e.g. notes to self). OTOH, maybe with message search, perhaps "AI" assisted, it might not be needed.
One use case for this sort of occasional "notes to self" and later search/gathering that I've been thinking of recently is for a shopping list, but it would have to involve basically zero effort to be useful. The idea would to allow you to say things like "shopping list: milk, bread", then next day "shopping list: cat food", then next day "show shopping list", or something similar.