Not sure if this counts, but someone I know made a javascript interpreter that runs on ESP32, ported it to a smartwatch and wrote a whole open source operating system. He put it on Kickstarter and reached the goal. He now sells the result, and a second one for a different smartwatch: https://www.espruino.com/Bangle.js2

There's an app store here: https://banglejs.com/apps/, but all apps are free and open source in a single github repo.