The niche I haven't found on Lemmy yet is coffee – we don't need to replicate a subreddit for every brew method, but I'd love to have a general community for coffee bean reviews and brewing tips.

Lemmy or at least Beehaw tends to favour more general communities; I wouldn't mind seeing a general notetaking/pkm/digital garden community where we can share our high-level methods and philosophies without getting too deep into specific software issues.