Thanks, I wondered why my router kernel went from 4.xx to 6.1 after flashing OpenWRT, especially when MediaTek is notorious for poor kernel support. This actually makes me respect OpenWRT even more.
MediaTek is pretty decent in terms of open source support for their WiFi chips and SoCs, to the point of continuously supporting a long time OpenWRT developer (Felix Fietkau) to work on their OpenWRT device drivers. This is an effort that is independent of their closed source drivers for the same devices.
Doesn't mean everything MTK does shines under the sun, but in Linux WiFi, they are probably the most open and well supported in the modern age.
This significantly shrinks the number of devices they support, but the devices that are supported have their lifespans increased significantly