According to Sensor Tower almost a thousand developers earned $1M for the first time in 2021. Of those 581 are on App Store and 325 on Google Play.

Report also contains more information on app category distribution.
Sensor Tower: Nearly 1,000 App Publishers Earned $1 Million for the First Time in 2021
Reference: New data shows how many App Store devs earned $1M for the first time in 2021