All the snapdragon n20 ultra have the same motherboard. In the bottom image you can see the Note 20 ultra motherboard. All model numbers supported. What differentiates the different models is a solder bridge. I'm the top image you see the U 0 D W. The u is bridged in this instance, making it a Sm-n986u. Further, the motherboard type is detected by the bootloader and sets a board id (6,2,0,-;Machine model: Samsung C2Q CHN PROJECT - SM-N9860_REV07C (board-id,10)), that board id is then detected by the modem bootloader and sets the particular config file to be loaded based on the board id (549_a_0.mbn) in the case of the SM-N9860. This config file then sets the particular bands the phone supports. All n20 U support all the bands, they are just encoded by the board and the software. No amount of tweaking that I know of will get around that. You may be able to open the phone and solder a different bridge, but I'm not sure if there are any files put on the phone during the build, that cannot be overwritten.