>GrapheneOS does not have an equivalent of ublock origin built into the OS which I'd consider step 1 of fighting the problem.

Content filtering is built into the browser. GrapheneOS have always maintained that you cannot prevent an app from exfiltrating data, especially if it has internet access. Enumerating badness is an unsustainable approach they don't want to encourage. Instead they attack the heart of the issue with Storage Scopes/Contact Scopes/Network Permission/Sensors Permission etc. They allow aps to think they have full access when they do not, so you can control exactly what data they get in the first place. Maybe all of the other AOSP projects could contribute App Communication Scopes/Enhanced Clipboard Privacy and other things because this approach makes a lot of sense to me. Like preventing an illness instead of wasting energy treating symptoms.

>The "ideal android" in my head would just have a dynamic ruleset to patch/nop tracking libraries as the app loads, which as far as I know, nobody does that, eOS doesn't either. Kind of like Revanced but on steroids and built into Android.

Something similar was addressed some years ago as a feature request for GrapheneOS https://github.com/GrapheneOS/os-issue-tracker/issues/284. To summarise there was no way to do this without an unacceptable security cost to the OS, but this is sort of doable if you run your own userdebug build which you have the power to do.