@sunyo0
Settings > Location > Location Services > Network Location (GrapheneOS Proxy) - Or Apple Server, if you'd like. You can also toggle Wi-Fi scanning on (if that suits you) I haven't had an issue either way.
In the default GrapheneOS App Store, make sure you have all the Google Play Services dependencies installed, such as GmsCompatConfig and Google Play Store.
Uber works completely fine for me. I've had no issues. I have my location set up in the following way. What issues are you having? The community here is the best if people are having issues.