xYz Acting foolish for asking questions and explaining what happened on my end and making a suggestion for the Google Play install instructions? Got it. You are a great professor! Anyway, I don't ever recall being asked if I want install additional Google apps. If that is what happened, that is totally new to me and perhaps I just blindly clicked accept because on all the previous devices I installed sandboxed Play on in the past I never recall such an option. And besides, why is it even asking me such a thing anyway? If indeed it did ask, it was a single click type thing to get me to install all the Google garbage which I want nothing to do with. It's like the old days of installing a windows app and there's a small checkmark opting you into install five other apps you want no part of. And why would GOS have implemented this now, when it never was an option in the past?
Let me be clear that I can't imagine that GrapheneOS would implement a feature which automatically installed or even asked you to install lots of Google apps. That seems to have been confirmed by the GrapheneOS account in their previous replies in this thread.
The prompt for installing Google apps comes from Play Store and is a new feature of Play Store itself, not Sandboxed Google Play or GrapheneOS. The prompt appears after you make a new account in Play Store (and possibly also when you sign in to an existing one; I haven't tried that). Try it in a new secondary profile.
Here's what happens to me: I install Sandboxed Google Play in a new secondary profile, create a new Google account through Play Store, then allow Play Store to display notifications. After about a minute I get a notification in the notification drawer "Action required in Play Store" (by the way, this is the standard text that appears when Play Store wants to install something but it needs your explicit permission for it to do so). I select the notification and a dialog asking me to permit Play Store to install unknown apps appears, and I select "allow from this source". I get an additional notification about Play Store requiring an action, when I select it Play Store asks me if I want to install a range of Google apps. I toggle off the check marks for each app and hit Install (not sure why I wouldn't just close the dialog instead, but there you go). A system dialog then asks me if I want to install Gboard and a few other apps. I select Cancel, and the apps are not installed.