As for the Topics API, It looks like to be a new copy of FLOC, which flopped immediately on release, as no body adopted it other than chrome.
This is an excellent test of Google's ability to just push a very unpopular feature into Chromium derivatives.
Google has a lot of control over chromium, but I don't think its even close to how gimped AOSP is compared to Android google edition.
They set the toggle to false and deactivated any of the options to turn it back on. That's very different from removing a feature (or maintaining a legacy feature).
The only code they changed was UX-related and a single default.