Some Trunk Based Development teams do "branch for release" https://trunkbaseddevelopment.com/branch-for-release/ and some do "release from trunk" https://trunkbaseddevelopment.com/release-from-trunk/
Google gave numbers themselves - 95% of their devs are in one big trunk (formerly perforce, but re-written in-house in 2012). It's true that the open source facing teams are outside that, and have processes that are less lock-step than what they do in-house.
Android - Samsung, on each release (maybe not anymore), used to check all the composite parts of Android into one big trunk for themselves. Back into their Perforce.
> If you're making Google Chrome, you don't.
There's nothing stopping the Chrome team from doing Trunk Based Development on Github, and accepting unsolicited pull requests like any other team.