The electronics for compass directions are in the mirror, not the car's electrics. A Gentex will work fine. I have added several aftermarket mirrors (mostly to give me the Homelink and auto-dimming features). You only need one switched and one unswitched power wire.

 

Thank you. I was able to install a used Toyota Camry mirror. My research since my post has shown that pretty much all Gentex mirrors are compatible, except the connector, so I had to splice that in. The three wires were 12V power (when car is on), ground, and reverse lights feed, which tells the mirror not to dim when in reverse. In that order. My Honda Clarity had only these three, but for those interested, the other connections can be a pair used to tell side mirrors to dim as well, a pair for Home Link, an a pair for an external temperature sensor.