You are right, only actions matter.

I get it, the user interface of a degoogled phone may be the same. That's not my concern.

But is it "easy" to make the switch?

Well, perhaps I'm missing something, I'd love to be wrong, but it seems to me that Graphene OS or Calyx OS works on Pixel phones only, and I don't have a phone like this right now, and they are unavailable where I live, at least not easily available and a cost to buy one if not trivial to me. 

Is there an OS that will work on wide range of devices? I have a phone that is 3 years old, running Android 11 today.