[josecastillo]

I made an Apple Watch app and complication a few years ago that averages $800 a month. I don't put any money into marketing or search ads, and it's been feature-complete since 2019:

https://www.betterday.app/

The app is built around two small, simple features: today's date with a customizable format, and a three-year calendar so you can see what weekday dates fall on outside of the current month. It also supports several alternative calendar systems including the Islamic and Hebrew religious calendars, which I think may be another use case that drives sales.

Anyway: it's a one-time, two-dollar purchase that lots of folks are still finding and finding useful.