To expand on this some if you're more of a visual person:
If you open the keyboard application, (just called "keyboard" when you do a search in your applications.) the second tab is "Shortcuts". From there you can see an interface that shows and helps you change all the shortcuts on the system.
You can use the search feature to narrow things down quickly. The multiple "screenshot" shortcuts were nice to find for some common use cases I do.
https://rclone.org/protondrive/
Sometimes you don't even need the open-sourcing side of things. I use rclone for OneDrive and I doubt Microsoft open sources it.
That being said, the rclone proton drive docs mention it's a beta and it's mostly the API they need to work properly.