My main reasoning was, I use the bus when i'm out and about, I don't carry a laptop with me most of the time, I was unhappy with the way the bus times were displayed in the available apps, so I wrote it on my phone at work when I had a bit of time.
Most of the other things were just playing around with the limited access to the android api termux gives you. I actually prefer SL4A for android scripting, but it's been dead for years. It granted access to more of androids api than termux does though.