Perhaps look into rclone? I use it for google drive and `rclone help backends` show protondrive as a service.
@carlt4 Yeah I've tried it, and it doesn't work reliably sadly (it gets some of the files and then times out...).
I think I delved into the forums to work out whether I was doing something wrong and the answer as I recall it is that Proton (currently) actively blocks the type of access that #rclone uses.
#Proton keeps saying that there will be a #ProtonDrive app for #Linux soon though 🤞