The main driver for making it into an app and not just a web page was the need to send push notifications. Of course, I just needed it for myself: hey, it's time to stop working and start driving to school to pick up the kid – "notify me 30 minutes before the last period ends" given that the schedule is different every day; then I just shared it with other parents.

There is a web version (it's Flutter so it was easy to make one), but parents use the app much more often.