You could remove the airbag (without disconnecting it) and probably be able to see if that blue connector is there. Removing the airbag for a look is simple.
Of course, even if it is there it doesn't really help you that much - until such time as Tesla deigns us with the ability to unlock it as an option. I'd personally say it's pretty much a certainly that MIC SR+s will be offered it, and the jury is out on whether Q1 on Fremont cars will.
My gut feeling is that Fremont cars that don't already have it and should (LR and P) probably don't have the heated wheel hardware, and SR+ owners it's basically a crapshoot because you could have the hardware or not and it still wouldn't have been activated. Only way to be sure
is to check.
From 5:01 onwards in that video you can see how much slack is on the cable connecting the airbag to the car, so there's plenty enough to be able to see if the blue connector is at the bottom.
Of note in the above "steering wheel removal" video you can see quite clearly that he doesn't have that extra blue connector, but he also has the seam/non-metal scroll wheel version, so obviously wouldn't have it.
If you have the blue connector at the bottom, you have a wheel that is capable of heating. If you don't, you don't.