Went with the 5K Levoit Core Mini. It does not have smart app or AQI display and it suitable only for rooms upto 178sqft. The room I needed it for is 120sqft. It fit my requirements, has good reviews and was cheap. Its filter cannot be washed but it can be vacuumed. As long as it is cleaning the air I dont care what the display says. I would know if it is effective in a few days if my wife starts feeling better. As Tracer_Bullet said, at the end of the day it is just a fan with a filter, how complex can it be.
However, if I were looking to spend 10K, I would have gone for the Phillips AC950. Which I might as my second air purifier for the other bedroom if I find this Levoit one effective. These damn allergies leading to frequent and persistent cough and cold are pesky.