As you have discovered, Google Drive install creates a volume called GoogleDrive (no space in the middle). This is not a real volume in the sense that it is an APFS volume. Rather it is a bit of software magic. The installation also creates an alias
Google Drive (with a space) in your home folder pointing to
As far as I can tell, and if you have elected to "Stream Files", the cache for locally stored Google Drive files in in
If you have chosen to "Mirror Files" then all your Google Drive is synchronised to the location you specify. As before the installation creates an alias
Google Drive in your home folder which points to the location you have chosen.
Note that, unlike the current OneDrive, you make a clear choice between steaming and mirroring your Google Drive cloud.
The above all works with macOS 12.3 beta 1, so may continue to work (without a Google update) with the release of macOS 12.3 (in April??). Someone else may have a more authoritative position on that.
I am unclear as to whether Google Drive has or has not made the transition to the Apple File Provider Framework, but note that it still uses the green tick mark for downloaded files when streaming files.