I have been using rclone for the past couple of years to keep off-site backups of my files in addition to TimeMachine backups to an external drive. What was initially a simple Python script to perform these cloud backups periodically has evolved into a menu bar application for macOS.
ThriftyBackup's distinctive feature is that it warns you when your backup exceeds a given threshold. I implemented this because I was always forgetting to update my exclude file when I added huge files that did not need to be backed up (such as virtual machine disk images).
If you want to give the app a try, please read the README at the GitHub page. You can download the app bundle here: ThriftyBackup-0.0.1.zip. Note that this is an Apple Silicon app, so it will not run on Intel Macs.
So far, it has only been tested on my own machine. I could have easily missed adding something important in to notes, so please let me know if it doesn't work for you. Unfortunately, the app's stdout/stderr output cannot easily be inspected, so it's not straightforward to debug.
If you are familiar with Python, you can also clone the repository and run app.py with Python. This will also work on Intel Macs. Just make sure to use Python 3.11 and install the dependencies listed in requirements.txt.
@jwink3101 Tagging you because I have the impression you might be interested
It uses APFS snapshots as the source for the rclone sync. This ensures that files do not change during the sync (which can cause some difficulty for rclone), and more importantly, it allows first scouting which files would be synced (rclone dry-run) and then performing the actual sync after checking the threshold and awaiting user feedback.