The paradigm isn't that we only support Pixel phones.

The paradigm is that only Pixel phones support our needs.

Only Samsung offer comparitive hardware to meet our requirements however they are hostile to alternate OSes as when unlocking the bootloader (required to flash one) they use Knox/efuses to break that hardware indefinitely even when returning to the stock OS.

Every other OEM cuts corners in this regard to cut down costs and increase profit margin. Many don't even properly support the hardware they ship with prompt security/driver/firmware updates.