I think an online personal file storage system would be great to have. But the way Google Drive and proton drive work is not good. They are designed to let the company control such files. I think we need a new take that gives more control to users. A private blossom server, where you can have decrypted files for yourself could be a simpler start. If it is not about sharing access to them, all it needs to do is to sync between devices. If it is about sharing access or even enable collaboration (allowing friends to save into your space), then I would say that it is a different solution and it might be a different app just for that.