I’ve written a plugin app for Tasker which allows running rsync over SSH from your Android device.
This currently has some rough edges (no support for host-key verification, unclear error messages) but I’m using it on a daily basis to backup files from and sync photos & music to my phone and am pleased to report that it works well.
Sadly Google rejected my submission of this app to the Play Store (and my subsequent appeal), due to the use of the MANAGE_EXTERNAL_STORAGE permission which is needed for the app to be at all useful. This unfortunately means that the app has to be manually downloaded and installed but I will be adding an update notification in the near future to make it easier to keep updated.
29 May 2022