Pixel Tablet does not have GPS built in. I had not known this prior to installing Graphene OS. I also didn't realize this when purchasing the tablet.

So it was to my surprise when I wasn't able to use Organic Maps or OSMand. It took some research but I was able to figure out a way to get it to work without purchasing an external GPS antenna.

Pixel Tablet (Graphene OS)
Settings > Apps > Sandboxed Google Play > Reroute location requests to OS - Turn off
Google Play Services - Location Permission to Always or Allow Only While using the App.
Turn on Nearby Devices Permissions
Connect Pixel Tablet to your phone. I have Pixel 6 Pro with Graphene OS.
Also Turn on Ultra Wide Band, search Settings for this. Or Long Press Bluetooth Icon and select Connection Preferences, turn on Ultra-Wide Band

Pixel Tablet Wifi On, Pixel 6 Pro Wifi On
Location works

Pixel tablet Wifi OFF, Pixel 6 Pro Wifi On
Location works

Pixelt Tablet Wifi Off, Pixel 6 Pro Wifi OFF, 4G/5G ON
Location Works.

Pixel Tablet Wifi Off, Pixel 6 Pro Wifi OFF, 4G/5G OFF
Location Works. I was surprised at this. But I guess since I still had cell service, it worked.

Pixe Tablet Wifi Off, Pixel 6 Pro Wifi Off, 4G/56 OFF, Airplane mode ON
It worked! Just make sure to turn Blue Tooth back on after turning on Airplane mode. My guess is that Pixel 6 Pro does have GPS, so it must be using that and sharing the location with Pixel Tablet?

I'm going to take the Pixel Tablet on the road with me to see if it works on the road. When I turned off Bluetooth and Wifi on Pixel Tablet, it seemed to still find the location. I don't know if that is because i was within Wifi Range and near my phone. But hopefully it'll work on the road/away from house.

Also it is quicker when using Location Services to Always.

If someone knows how to get Pixel Tablet to use Location Services with Using Reroute location services OS, I'd like to implement that.

Graphene OS is great. Thank you all.