One profile is a good plan and helps a lot with sticking with it.
Being downloaded from the play store doesn't necessarily mean the app is dependent on play services. There's an app called Plexus that can help you check, I have actually found basically all of my major US banking apps work without play services. I am not sure about living across profiles but I think for push notifications to work you need play services to be installed in that profile as well but I could be wrong.
The method that worked for me was to install everything normally in one profile and then see what apps actually required play services and slowly transition one at a time to either an alternative or to the setup I have now which is degoogled main space and play services in the private space.
Yup have to embrace the tinkering haha. Good luck!