Device folder-level access control
Now that the entire contents of my Proton Drive are accessible from all devices that I log into it with, I'm nervous that a compromise on one device could lead to a complete takeover of all my data.
I'd like to suggest a feature where folders can be given an access control list, similar to NTFS permissions on Windows, but device based. The web portal would have access to all folders always, but from the web portal, you could define which devices are allowed read/write access to specific folders.
This would allow for segregation of my data, and give comfort that one device can be granted access without having to worry about all my files being visible to that device.