As someone else has probably already suggested, the drivers for the on-board sound and Ethernet are just not finished yet.
I suppose it could be a botched motherboard design and they don't work, but I think that is unlikely. Drivers take time and effort to write and manpower is limited, so I would not panic yet.
I need to go back and read some previous pages of this thread, I don't know where this came from. But let's assume it's true, and that your list (ethernet, sound) of not yet working drivers is complete. (I'll assume that you'd list more if there were more to be listed)
If the board is botched, then thre would certainly be more things on your list. Sound is inside the sb600 southbridge, same as SATA, USB, and other things.
Though the SB600 does not include ethernet, so that's obviously a separate chip, and has some chance of a board defect independent of other board features.
I'll assume that they are NOT using the 10Gb XAUI inside the 1682M for the X1000 ethernet. I don't believe this is compatible to 10Mbit/100Mbit/1Gbit, and I do believe that they will have used all available SERDES pins for PCI-Express instead.
Drivers take time, that's why the board is not available for public sale. Beta testers will check this all works when available to them. They're probably using PCI/PCIe sound and ethernet cards that already have drivers until these new drivers are done, so they're not super-suffering. If they do find a board defect, that's what the beta program is for, they'll fix it and we the public won't suffer when final production boards are selling at our local Amiga internet store. Non-beta-testers like me don't need to care.