For my Android Note App I do encrypt data before backup (End-to-end encryption), so even if someone can get data, they cannot read it.

You can try to follow my solutions

1. Export data to JSON file
2. Zip JSON data to minimize the backup size
3. Encrypt zip file
4. Upload encrypted zip file to clouds or somewhere

To implement step-1 to step-4 quickly, you can checkout my opensource library. My library support methods for convert data to JSON, zip file, encrypt/decrypt data easily.

Git Hub: https://github.com/vuthaiduy1990/android-wind-library/wiki