Sporeondeloreon Do you know if the shared connection for internet access needs to be a certain speed for this to work?
There is no shared connection. The device running the GrapheneOS installer needs some kind of Internet connection -- faster is better, because the download is large, but it's not super-gigantic, so there is no need for a gigabit fiber connection. The Pixel which GrapheneOS is being installed on will be off of the network because it will be running the bootloader, not a regular operating system.
Sporeondeloreon The usb c makes sense to meet the high speed data transfer but isn’t that only as good as the laser ice signal and data speed?
The USB-C connection is not used to provide Internet service to the device that GrapheneOS is being installed on, because the device GrapheneOS is being installed on will be off the network, because it will be running the bootloader. The USB-C connection is used to carry out brain surgery on the Pixel device.
Regardless of whether it seems to make sense to use a USB-C connection, there is no other way to install GrapheneOS on a Pixel device. It's not a matter of opinion, or a best practice; it is just the only way.