DeletedUser159 what are you referring to by saying 'is it worth it?'
If you mean installing GOS, then I would say yes. GOS is designed to run Google services (in a sandbox env, optional)
I would just make a separate user for Google services and use another for everything else
"If I am installing Google Play Services on GrapheneOS, does it reduce privacy", yes "and security", no
Simply make a new user, setup your user, then go to 'apps' and install google play services. Once done you can open google play and sign into your account like normal