Gmail is 1 part of the puzzle. A big part but still one part. But when you give something access to your email, calendar, iMessage, browser, passkeys of other apps, location it can autocomplete the missing parts and can pretty much complete the jigsaw.
I would never run Grok Bot or Muse with any sort of authentication.
I did try booking a flight with Muse and it worked surprisingly well. But I never used it after.