charris86 I didn't watch the whole video, but it looks like this person did install GrapheneOS correctly using the web installer, then installed Google Play correctly using the GrapheneOS Apps app, but after that they just started changing permissions for all sorts of apps. One app was Google Play Services which they disabled the network permission for. Google Play Services, I'm betting, would need access to the internet for Google Fi to work.
Also, they changed permissions for all sorts of other apps that I'd suggest not modifying, like the phone app, messaging, etc. Basically, don't change permissions for any apps unless you were the one to install them.
If you also changed permissions for random apps that you didn't install yourself, then you might just want to factory reset your phone and start over again.