Lil heads up for google one users with a pixel 7* & pixel 7 pro*
As of December 2022, Pixel 7* and Pixel 7 Pro* consumers can access VPN by Google One at no extra cost on those devices through the Google One app without a Google One subscription
If you have one of they devices install the google one app to benefit
Thats if you wanna trust a VPN service by google
So far i can't find anything to suggest google are using another VPN service to use for their VPN
6 question's you might have about VPN by Google
https://blog.google/products/google-one/common-questions-vpn-google-one/
all other google one users need to subscribe to the 2TB deal to get the VPN as an extra
google claim
Our client libraries are open sourced, and our end-to-end systems have been independently audited.
source code >> https://github.com/google/vpn-libraries
independant audit >> https://research.nccgroup.com/2021/04/08/public-report-vpn-by-google-one-technical-security-privacy-assessment/
more here
https://one.google.com/about/vpn