[Fnoord]

PC Engines APU [1] and APU2 [2] come with Coreboot as firmware. As do various competitors [3]

[1] http://www.pcengines.ch/apu.htm

[2] http://www.pcengines.ch/apu2.htm

[3] https://store.netgate.com/ADI/RCC-VE-2440.aspx