And also what is it that we are looking at in that pic?
Thats a pair of 6xQSFP28 adapter that connects to the FPGA transceivers, with 100Gbps Direct attach cables.
Aka as 6x100Gbps worth of interconnect between two more typical Virtex development boards.
If you need more FPGA to FPGA connectivity, the XUPP3R also has an onboard expansion connector with 20 transceivers, and a standard cable that can connect two boards together. So 4x 100Gbps QSFPs on the front, and another 5x 100Gbps on an expansion connector. That means you could daisy chain with 400Gbps FPGA to FPGA.