graphene_user If I were to use a single profile, but disable location permissions for the Google Services, would that also prevent excess location data going to Google?
Yes.
Isolating Google apps in a secondary profile is useful if you want to prevent them from seeing the other apps you have installed and/or prevent them from potentially communicating (in basic ways) with your other apps and managing some functionality for these apps (such as notifications through FCM). Using multiple profiles isn't required to benefit from the privacy and security enhancements of GrapheneOS and it isn't necessary at all in order to greatly restrict the amount of data Google can access on your phone through its apps.
If you manage your permissions correctly, there is no need to use a secondary profile just to prevent giving Google access to your location. Just install Google apps in your main profile and deny the location permission for all of them aside from Maps, and grant it only the sufficient location permission ("ask everytime" or "while the app is running").
Running Google apps isolated in a secondary profile restricts the information they can access even more but it sometimes comes at a usability and convenience cost that can easily be deemed not to be worth it, since many apps rely on Play Services for functionality and switching profiles isn't seamless.