Half techie guy here with basic question. Could I run this on an old android phone sitting on a shelf with a large minisd card in the slot and call it a day?

Yup, here's a timestamp to the intro video where the author says it was "made for termux, born in termux": https://youtu.be/15_-hgsX2V0?t=889

Yeah, I'm fairly certain you could run it on an android device using termux.

You'll likely need to root the phone to get the OS not to kill the termux process due to idleness though.