Google gets its way, bakes a user-tracking ad platform directly into Chrome

probably already has. They put things into chromium first, then move them to chrome usually.

Vivaldi will never have it

It's been in there for weeks/months: https://chromium.googlesource.com/chromium/src/+/refs/heads/main/components/privacy_sandbox

Most if not all other Chromium-based browsers have disabled it though.