OldFartCracker i had same issue and got i working on pixel 9a by going to settings >Location >Location services >Network location and selecting GrapheneOS proxy. All other options in location settings is still off.
I just enabled them one by one and restarted the app every time to find a working combination.
The app has permission to use location "while using the app" and precise location is enabled.
In settings >Location, SUPL and PSDS are set to GrapheneOS proxy and GrapheneOS server respectively.
In sandboxed Google play I have "reroute location requests to OS" enabled.
Hope that might help get it working.