I see some core team on this thread, so just wanted to say THANK YOU! Awesome job! Keep fighting for the users!
I'm totally the wrong person to offer recommendations on mobile, but so far it works very well for me, but then, I use almost no third party apps, and none of them are Play store only. My only complaint is the hardware (outside of their control).
It's fairly pointless for apps to check for Mock Location being active without also verifying the OS via the Play Integrity API or hardware attestation API. Most apps checking for it are using or in the process of adopting the Play Integrity API. Apps enforcing the Play Integrity API basic/strong integrity level won't work on GrapheneOS unless they explicitly allow it. A growing number of apps doing this are explicitly allowing GrapheneOS. It would be counterproductive if our Location Scopes API didn't provide a way for apps to check if since those apps simply wouldn't permit GrapheneOS. However, it doesn't need to be the existing Mock Location API. It can be our own API which would only be used by apps explicitly choosing to permit GrapheneOS. This would allow apps like Pokemon Go and Ingress to permit GrapheneOS even if they insist on not allowing directly spoofing location.