You may have seen releases for GmsCompatConfig before. This is just a text file that sets up configuration for GmsCompat.
Some config examples are the type of data to return to Google Play when it attempts to do privileged functions. The sandboxed Google Play compatibility layer acts as an intermediary to allow app compatibility without privileged access.
https://github.com/GrapheneOS/platform_packages_apps_GmsCompat/blob/45b13b45de7c76a528cdc236d66d3184595cd99a/gmscompat_config