On linux it turns out you can just use gnome’s online accounts to connect to google (and i suppose KDE has a version too). The drive will appear in your file manager (file aka nautilus) as firstname.lastname@example.org. You can then use the ‘normal’ way of opening all your files located on your google drive.
I was puzzled by this too. I do not want to give my phone number to google, then what? Would be nice if a user can choose which authentication method to use in the first place and that libreoffice is just recognizing the gnome online accounts already created and lists them automatically in the remote services.
One thing I noticed. I cannot open files from the filemanager directly by double clicking a file as the google-drive file format was not recognised.
I can open them via libreoffice directly