Soooo ... I finally built up my BrewPiLess / BrewPi-8266 based on @LBussy 's PCB, printed a 3D enclosure and everything and ... no dice :(
I flashed manually, I flashed using BrewFlasher but all I got is
16:46:27.383 ->
16:46:27.383 -> ets Jan 8 2013,rst cause:2, boot mode:(3,6)
16:46:27.383...