We recently switched from a white 2017 XF Prestige (which we bought new) to a red nearly identical one (because the white one met an unfortunate and unlikely end). The features in the second one are close with a few exceptions. I'm baffled at the lack of Homelink garage door buttons on the red one - I thought almost all cars of this era and beyond had them. As we were removing items from the carcass of the white one, I removed the rearview mirror too in case it could be used on the red one. Question: are the connections for the Homelink system in the housing of the rearview mirror even if the mirror does not have the buttons? Could I switch mirrors and have an operating Homelink system?

Yes.

Homelink is completely self contained and only requires a power connection.

All I had to do was replace my receiver in the garage because UK Homelink mirrors are like unobtainium and work in a different carrier frequency.