I'm under no illusion that google doesn't know I own my multiple accounts. They most certainly do. I usually use the same user agent (with containers) on the same IP, after all.

But my goal is to avoid a stranger gaining access to my google services if they manage to unlock a lost device or steal my TV/streaming box that has no lock at all.

I wish Google supported a permission system per device. For example on most of my android devices all I really want is to be logged into Youtube and the play store. I most certainly do not want those devices to have access to my contacts, emails, calendar, keep, drive, payment, etc. (I don't personally use all of those things, but you might and that's what a random thief would gain access to.)

Yep, something like checkboxes on login:

   - ALL: Log me in to all Google Services
   - Calendar
   - GMail
   - YouTube
   - ...