You can always give the possibility that the user enters his API key to Pushover and by pushover you can receive push notifications, I have already written many

You can always give the possibility that the user enters his API key to Pushover and by pushover you can receive push notifications, I have already written many programs that work with Pushover, one works to this day, every 6 hours I get the current price of bitcoin back with a difference whether the price has decreased or increased. It's really convenient, I don't even have to pull out my phone because notifications come straight to my Apple Watch.