I think they don’t even have basic location mocking. They have disable or enable. But some apps won’t work.

Mock Location is a standard Android feature available in GrapheneOS. Our upcoming Location Scopes feature is being added for per-app control rather than global.

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.

I believe this is in the works: https://bsky.app/profile/grapheneos.org/post/3lqbhoqwrjs2y

My understanding is that Mock Location on android is a developer setting that apps can easily check for, and as such, is basically useless (it will not fool any app that is asking for your location).

It's basically only useful for debugging.

Not by default, but there are several apps on F-Droid that do this