It’s not fancy like an automatic folder sync thing, but at least I could mount a Protondrive directory and do my own syncing myself (I’m a Linux nerd afterall). There is no need for “deep filesystem integration” as he claims.

The same thing could be used for Calendar with Caldav feed as well. A single “Bridge” app could me made to handle Mail, Drive, Calendar

ProtonDrive bridge (like they have for Mail), that handles the encryption, that exposes a localhost webdav endpoint that can be mounted.