alt Hacker News> this also sort of defeats the purpose
Not really. On GrapheneOS, the Play Services/Play Store run as sandboxed apps, i.e. they are not system apps like on Android. They just run like a normal, unprivileged app. That's a lot better than on Android.
> I'd rather break free from Google and Apple, not just (stock) Android and iOS
If you want to break free, you don't have to install the Play Services / Play Store on GrapheneOS, just like you don't have to install microG on LineageOS. There is a misconception that microG is better than sandboxed Play, but I disagree. With microG, your apps still connect to the Google servers, so you're not "breaking free".
With microG, your apps still connect to the Google servers, so you're not "breaking free".
Moreover, some OSes (e.g. /e/OS) give certain Google apps higher privileges than other apps even with microG, install Android Auto and it's still game over. GrapheneOS does not have this issue because as you say, Google apps/services get sandboxed.
Obligatory link: https://eylenburg.github.io/android_comparison.htm