I have been playing with one of these for a few weeks, I was actually working on documenting some of my findings but haven't gotten far enough to post something yet
but I can answer some questions
It runs ESXi 8
1x Intel I210 is connected to the management port
2x Intel I350 ports are G0 and G1- only the SFP ports work, NFVIS software must do some magic to make the RJ45s work
2x Intel XL710 ports are connected to the internal Marvell switch @ 10Gbps
Onboard Intel X552 does not seem to be connected to anything, boo
Power draw is 28W with only CIMC booted, 65W with system running, 85W max I've seen (excluding POE)
The internal Marvell switch has 4x 10Gbps ports, 2 are connected to the main system XL710. The switch does not have any flash, it's booted with a special procedure from the host CPU (more on this later if anybody cares). The XL710 supports VM-to-VM accelerated networking and I am able to get about 30Gb/s between VMs using SR-IOV.
There are 2 expansion slots- 1 Cisco NIM slot and 1 internal "RAID" slot. I'm guessing these are PCIe with some sort of proprietary pinout.
I could not get an NVME to work in the M.2 slot despite the BIOS having NVME options and bifurcation settings available, may be wired for SATA only.