Switching between 500 mA, 2.1A, and USB-PD or QC is technically simple, but again you're making consumer electronics for a very, very small group of people.

How would it determine when the attached device reaches 80% state of charge? Or what the time of day is? How could you program a schedule for weekdays and weekends?

There are good reasons for Chargie to have an app, it's not just there to siphon up analytics.