I have done the equivalent for StrongARM machines, run NetBSD directly from the flash chips on the board without having Windows CE. This was to help with board bringup of Windows CE systems that we were manufacturing.
For the same experience now, just buy a Pinebook Pro.
Or a used ARM Chromebook. An Asus C100P in good nick is still quite nice IMO, aside from the lack of updates.
Official updates wouldn't matter if you were running NetBSD on it.