It is probably a SoC limitation... Feel free to suggest an alternative ;)
2. Mediatek might not be willing to provide their WiFi SoC if you are not using their compute SoC, and Rockchip doesn't have any WiFi chips.
The rk3588 is frankly a non-starter.
There are some China-only ZTE devices that do this, but they obviously have a different order volume and scale that makes it possible. (The main SoC is replaced with a ZXIC one, a ZTE subsidiary)