I'm inclined to say no. The US model just has a single wire connection from the body control ECU to each of the taillights, so it's on or off.
If I were designing the sequential rear tail light, I'd design it to take just power, with circuitry onboard to handle the sequential illumination. As long as the sequence time is shorter than the blink period of the power signal, you could power it with either a blinking signal or a solid-on signal and expect either to work just fine.
The key is that the US law requires the portion of the turn signal that initially lights up be a certain minimum size.
I think this is half
the gotcha. If they lit up the entire vertical part of the hockey stick, then sequenced down from there, that might be able to satisfy the regulation. But then the sequence would go against the turn direction, which would of course be silly. Otherwise you could do the entire thin bit of the hockey stick, but then there's basically nothing to sequence. The "start" of the sequence, given the visual design, is simply too small.
The other half
is that Kia was clearly cheap AF in a bunch of spots on the US spec car, for instance the missing dashcam and so forth. In the USA, since they can
get away with using the same lamp for brakes and turn signal, that's one less lamp to have to spend money on.
When I had my rear trim panel off to run my dashcam, there was a couple unused plugs on the same harness that was feeding the upper turn signal/brake light.
This is EXACTLY what i'd expect if they were plug and play compatible between regions. Was there ONE disused plug per side, or were there two?
i'm sure it would require some type of coding even if those plugs were meant for that lower turn signal.
I'm not convinced without more digging. One possibility, especially if there's one disused plug, is that you plug the lower blinker into that, and then you do
have to make some region configuration change to drive the right timing to each plug. Another possibility is that one plug is "blinker" and the USA-disused plug is "brake light only." Swap the existing lamp down to your new euro-spec blinker, and connect the disused plug to the existing brake lamp to take blinker functionality off it.
If the disused plug and the currently-used plug are physically interchangeable, I'd put money on it's plug and play. That would be a bit of an assembly nightmare though so I wouldn't be surprised if it IS coding-required.
Might have to pull off that trim panel and have a look myself with a multimeter. How'd you get in there exactly?