Put the Chromebooks in their own group
Make an organizational unit just for the Chromebooks that will run Genesis, for example Genesis Carts, and move them into it. Every setting on this page goes on that group, so nothing else at your school changes.
New Chromebooks? Enroll them first. At the sign-in screen press Ctrl + Alt + E and sign in with your school's admin or enrollment account. Do it before anyone signs in; if someone already has, reset the Chromebook with Esc + Refresh + Power first.