Change multiple materials with keystroke

I have an interior visualization I’m working on for a client and they have two different versions of the same space. I’m wondering is there a simple blueprint using a keystroke to swap the materials from scheme a to scheme b rather than building two separate levels?

Ideally pressing A would show the materials for scheme and and pressing B would show materials for scheme B.

I know how to apply a keystroke to change a material on one object but unsure on how to apply it to multiple objects.