Yeah same in fact that's how I discovered Termux. I had an rsync.net account and thought that since rsync and ssh are so ubiquitous it should be simple to set up back-ups from my android phone. Boy was I wrong. The android apps that support rsync were all janky or suspiciously closed. Termux + rsync + Termux API's job scheduler does the trick. I think it's a bit of a drain on my phone battery but I won't complain given I own my photo back-ups from top to bottom (though I rent from rsync.net)