Super Micro builds custom designed boards for other businesses given the right quantities. It's a huge part of their business; I wouldn't be surprised if it's bigger than their white box boards.
One of the allegations was that special purpose video encoder boards from a hardware startup that Amazon acquired (Elemental) were targeted. These aren't off the shelf boards that anyone can buy.
No, just that the a absence of evidence isn't the evidence of absence.
There's next to no way that Bloomberg's sources would still have access to the boards, and that should be considered given all of the calls here to see them.