You don’t have to use Google services. They are fully optional, and not installed by default. AOSP/GrapheneOS without Google services is very usable, there are only very few things you can’t do without proprietary services. You still have the option to create a separate user profile (which are also improved by GrapheneOS btw) to install Google Play services, and keep it isolated from the rest of your apps and data.
You don’t have to use Google services. They are fully optional, and not installed by default. AOSP/GrapheneOS without Google services is very usable, there are only very few things you can’t do without proprietary services. You still have the option to create a separate user profile (which are also improved by GrapheneOS btw) to install Google Play services, and keep it isolated from the rest of your apps and data.