Naven
Answers
Do you need a Google account to use Naven?
No. Any email address works — Outlook, Yahoo, iCloud, a work address, a school address. Naven emails a six-digit code to whatever address you give it.
Signing in with Google is offered and is not required. The default route is a code, which works with any provider and does not involve a third party in the sign-in at all.
This matters in places where Google's domains are blocked, and it matters for anybody who prefers not to attach another service to their Google account.
There is also no phone number involved on any of the routes.