

This. It’s not as simple to get it working as it is on non-free OS’s, but with rclone I can get on Linux pretty much the same functionality I get from (eg.) Google Drive on Windows, including have most of the drive with on-demand access (meaning files are not stored locally, but downloaded / uploaded as needed) with a few specific folders synced for offline use. Since it supports a lot of storage services, I suppose it shouldn’t be that different to set it up the same way with Proton Drive.
Linux can read and write to NTFS drives just fine. Just make sure you’re using the newer native (in-kernel) driver, ntfs3. The older user-mode driver, ntfs-3g, still works but has much worse performance, which I guess should be a concern if you’re going to run games off of it (ntfs-3g is fine for casual use)