This product is being cast as 'AppTrackingTransparency for Android', but that's not quite right — it's actually a VPN-esque system, similar to a number of others already on the market (for example, the third-party Lockdown Privacy service on iOS).
The premise of solutions like these is basically more like an ad blocker: by re-routing all outgoing network requests from an app, it's possible to block traffic to any URL flagged as a 'tracker' on a static list.
Obviously, the definition of 'tracker' is subjective, and this is a sledgehammer-type solution that can have sledgehammer-type effects on app functionality: one of the app categories that DuckDuckGo currently excludes is 'all mobile games', because they found too many of them stopped working.
With the increasing impact of privacy regulations, limitations on mobile device IDs, and looming deprecation of third-party cookies, 'data clean rooms' are becoming a hot topic. Like Switzerland for data, they promise a solution for aggregated audience insights, without requiring brands to expose PII across companies.
Of course, user consent is still technically required, and a clean room is not a silver bullet...
“A clean room is not a washing machine, you cannot throw your data in there, throw a tide pod in, and think that it’s okay to use […] Be very cautious about being told that a clean room is going to solve all your problems.”