For Google Maps, they refuse to even store local search history or use the local Address Book API to get your home address: to get either of these basic features you have to sign in with your Google Account, and to get the former feature you have to turn on saved search history for your entire Google account including normal web searches, and I imagine for the latter to work you need to turn on location tracking. Google acts maliciously with respect to obtaining personal data and clearly is never going to implement end-to-end encryption as it fundamentally undermines their mission of "organizing the world's information": they can't organize what they can't see.

It's hopeless. Google has already given up on a bunch of end-to-end encrypted projects, and now I've noticed they've added automatic backups of messages to the cloud for Allo, which may include the messages in the "Incognito mode" (I'm not sure, but I wouldn't be surprised if they did that).

I've already moved on to ProtonMail. The days of Google being the "good guys" that will fight for you are over.