Are there any pictures around of these 8, 16, 32 socket boards? Just curious how they look like.

The individual motherboards have only four sockets: https://assets.ext.hpe.com/is/image/hpedam/s00012647?$zoom$#...

Multiple of these can be linked together with “NUMALink” cables, which carry the same protocol as the traces that go between sockets on the motherboard. You end up with a single kernel running across multiple chassis.