What is going on is frustration. GrapheneOS has been relying on Google's good faith effort on providing binary blobs to Pixel in addition to AOSP to make their OS. Google was under no obligation to give that, and they stopped doing it for whatever reason.
To make things worse, GrapheneOS mentions legal/anti-trust blah blah blah, which means no engineer will touch / comment / help in the matter, and it gets routed to legal blackhole.
The hardware support is nice, but even without it it's still vastly more secure than stock android.
Non-Pixel devices usually require you to just give up secure boot, in this case a GrapheneOS install could be even worse than stock Android.