Google is one of the few free mail+everything+else providers that still lets people sign up and not give any kind of real-world identity. So you can, on a clean phone or laptop or whatever, create a new gmail account without any kind of auth and maintain that persona.
In practice this isn't how people are using google services though.
I made a Google account without even owning a number a few days ago. Afaik only one of my Google accounts has a phone number and pretty sure that's only because AdSense.
My tinfoil hat theory is that if it doesn't ask for a phone number then it already has a very precise shadow profile about you. Being on linux+firefox+grapheneos compared to windows+chrome+android probably means a lot in that regard.
In practice this isn't how people are using google services though.