I also am very happy overall with my EV6, the ride, handling, power and range are great. But there are a few UX and software gaps that keep the car from being all it could be. I have only had the car for one week but found several things that seem like they should be easy fixes, and hope that Kia engineers and marketing reads the forums
I have the same thoughts about the HUD on my GT-line, it would be nice to be able to move it a bit lower. I have not experienced the issue you described with the LKA feature. But it would nice to be able to turn the LKW off when driving in the city, it is annoying to have to always use the turn signals to prevent beeping when changing lanes at low speeds, and it also sometimes beeps incorrectly due to bad lane markings and or cracks in the pavement.
Another bug that has been previously reported and should be any easy fix; if I open the hatch first before getting into the car, the automatic approach unlock function does not work. I find that you have to use the key fob button to unlock the car after that. Overall the lock and unlock functionality is very dated and needs me to use the key fob more than necessary to lock and unlock.
Also, I was surprised to find that once I set a charging schedule there was no button to tell the car to start charging immediately, even my first gen Leaf had this button! Without turning off the scheduled charging the only way I found to get it to change immediately, was to use the Kia app. I guess this is one way to be sure people pay for the app once the introductory period expires.