GrapheneOS also heavily promote the use of open source Android apps. What they refuse is having app stores that reuse app package names, centralise the signing of app packages, perform reproducible builds on outdated infrastructure, significantly delay app updates et cetera.
I cannot deny your opinion, but just want to suggest that from my understanding GrapheneOS are not against microG and F-Droid as concepts, just against their current implementations.
From which follows that, just like Google and Apple, they must protect your device from yourself, and therefore they too won't let you own your device.
For me, it's not shady in any way - it's just the same stuff as the Big Two, just with different branding and different organization behind it.
If I was reading this critically I'd say you have an axe to grind and want to continue to show why HN is a useless source of news or content.