There has been a lot of misinformation over the years on whether or not Google Drive supports "differential" uploads. However, they specifically state in a recent changelog:
October 21, 2024 - Bug fixes
Windows and macOS: Version 99.0
- Added support for “differential” uploads. When large files are edited, Drive for desktop will now upload only the parts of the file that changed.
- Bug fixes and performance improvements
I'd like to see if others have a shared interest in this and if someone with experience in dissecting Windows apps & network traffic would be willing to take a look to see if they are using undocumented APIs? I'd be curious to learn more about the block size & implementation details. I've long pondered if there was a way to utilize resumable uploads to only modify parts of a file, but I'm guessing they're probably using undocumented APIs.
While differential uploads on select cloud providers may not be considered immediately rewarding for the project as a whole, especially since rclone connects to so many, this could be of interest for a potential contributor to explore some features utilizing it. I've thought of some unique cases involving encryption, as well as container formats that could be designed or adapted for efficient differential updates.