Yup, after years of trying to make nextcloud, syncthing, etc work for my workflow (copy from flat photos folder on device -> flat photos staging folder on backup server, then a cron job organizes it into folders by year/month), I finally resorted to something manual. Termux + rsync on android. Every few days, I run the termux shortcut to rsync a folder, and delete what's copied over from my device. It just works.