My portfolio of iOS apps ends up at an average of $500/mo.

Most are older, still functional but rarely updated. A few of the newer ones include:

https://daylightgoals.com - Time in daylight tracker, using Apple Watch/HealthKit as the data source.

https://airlauncher.app - App launcher for visionOS - was much bigger last year before Apple added the ability to organize your apps.

https://itunes.apple.com/us/app/ibuzz/id304684758?ls=1&mt=8 - iBuzz - I built this app in a day 15 years ago, it still makes about $100/mo from ads and removing ads. Just a simple buzzer soundboard app.