DeletedUser88 It's hard to say, since there isn't an implementation to try.
Personally I am a bit skeptical about IPC filtering. I suspect lots of IPC activity that people want to filter out is already not happening, and also that a lot of people will find that filtering apps from talking to Google Play will just cause those apps to throw an error and quit.
Like any control mechanism, it will likely have uses. But if people have a vision that IPC filtering will convert spyware apps into privacy-preserving apps, I don't think that will come to pass.
And I think it may be fussy to set up. If an app is allowed to do IPC for clipboard purposes, that's non-trivial attack surface. But if an app is denied clipboard access I think that will be annoying. If a new keyboard is installed, will it be necessary to authorize each app to talk to it?
Overall I am not expecting it to be a giant positive life change for most users. I suspect most GrapheneOS users would benefit more if upstream AOSP glitches in the profile system were fixed (hopefully by Google).
But maybe I'll turn out to be wrong!