I think this is probably correct.
In theory you could order the battery heater and figure out where to install it. You might or might not be able to figure out how to get it wired into the rest of the car. But the software thing is going to be the deal breaker, and I haven't heard anything about a Hyundai or Kia owner getting that turned on by the dealer.
The heat pump is likely to be even harder, even more expensive, and even more unlikely to get successfully installed. We would almost need someone to do a tear-down of a model with and without to figure out what's needed (aside from software), and I don't see anyone volunteering.
Getting back to the battery warmer, I can make a couple of observations here. First, if you are charging at home, the battery heater isn't needed at all. The main advantage of the battery warmer is that it helps with DC fast charging - making that charging a bit faster. Even then, it would still take some number of minutes for the battery warmer to warm the battery up to the point where faster charging even kicks in.
Secondly, there is some amount of waste heat in the electric motor, and this is captured and used to warm the battery. In the winter I would sometimes take several hour drives, and I got into the habit of going to the DC fast charger right after the drive so the batteries would be warmer, and this helped a lot (note - I have a Kona, but I believe the Niro drivetrain is pretty much the same). Going to a fast charger first thing in the morning when everything is
ice cold results in some pretty poor charging speeds. If you were on a long road trip, the batteries should already be warm.
I believe the battery warmer also helps protect the battery from damage in extremely cold temperatures like they have in some parts of Canada. But in the U.S., there aren't that many places where it gets this cold. If you have a heated garage where you park the car, it is even less of a consideration.
For normal driving at highway speeds, my recollection is that the power consumed was something like 15kW or thereabouts - if the electric motor loses 10% as heat, then you effectively have a 1.5kW heater warming up the battery. So my guess is that something like a 30 minute drive is probably all that is needed to warm the battery in preparation for charging. If you had one of those OBDII readers, you would be able to check the temperature as you drive and see for real.
