well about hacked together they all use the same bsp to get their precompiled libraries and they all use the same dowmstream kernel .
there is just some diffrences from wich date they based their kernel from the dowmstream one , and some drivers for khadas edge2 the mcu or small difrent lcd's screens in their shop or other wifi or net (opi5)
and 1 use the "not official" panfork mod and the other the default mali blob
and pd issue 5B i dont know use a xiamo charger wich got free with a phone and happy does 20V and the sd reader is crap
and the nanopi kernel is the most modded one with their openwrt things etc
and for the OS it is just how you configure it and if you like the khadas ubunutu more as stock raxda os then use khadas ubuntu on a 5B
how is the av1 and avs streaming is going on other distros as armbian or wich board has it supported ?