As far as I am concerned, the BBoAH should really only contain information about hardware built specifically for the original Amiga machines. So, while info about a particular PCI expansion bus is useful, I don't feel there's any value in including information about generic PCI cards you'd put in there. Possible exceptions to that rule being perhaps lists of known compatible devices.
Regarding "NG", it's a bit muddier. Nobody can seriously claim that OS4, MorphOS and AROS aren't anything to do with the Amiga (though many try), so in my view it's fair to include information about hardware purpose-built to run these operating systems. So stuff like the A1, Pegasos, Efika, Sam and so forth are all valid entries.
Of course, generic PC's and PPC based macs are as much commodity hardware as anything else, so I don't feel there's a need to include them because as with vanilla PCI cards, it's all already out there. However, it would certainly be useful to include information about, for example, which specific models are supported. If you want a fully supported MorphOS, AROS or Amithlon box, it would be an ideal resource to check.