Were you getting Python errors from Restic? Not terribly familiar with Duplicity, but Restic is written in Go (Github is https://github.com/restic/restic).
I tried 4 different similar packages; maybe I remember that detail wrong, but I could not get Restic working on older machines for some reason. Rclone was so simple and it just worked, so I did not investigate further. Is Restic much better?
Yeah for me the hardest part about installing restic was remembering how to unzip a bz2 file. I don't know what more you can ask for than a statically linked binary...
Ok, cannot have been Restic then; thanks, I am going to try that one now. And find out what the other Python one was; I was following an SO recommendation.