This looks to be of interest to anyone with an interest in learning JavaScript.
https://www.phonearena.com/news/google-grasshopper-javascript-free-lessons-game_id104211
That's pretty cool! Thanks, Bill!
Note that coding on a phone can be complicated if you don't have a real keyboard (or full screen keyboard on a tablet).
But I remember reading this article about an African guy who wrote an app entirely on his feature phone. Feature phones are the old phones that only have numbers and a couple of other characters and tiny screens. To enter a letter, you have to push the number from one to three times. So you can imagine how much work that took!