I once wanted to build one like this, but for console devkits. That situation was and went, but I did end up wanting to have the same for all windows machines at work and home (Unity dev, so workstations, test runners even servers are desktop windows machines). My solution was: -BIOS: auto-power on when power is connected -Smart power plugs on important computers -AnyDesk for software on all machines, with unattended…
I went with a similar setup and the only thing I'd add to your list is using multiple NICs and having one dedicated for remote management.
Can I ask what is the exact point of adding more NIC's? Considering one can just hard reset the machine remotely, a network card driver goof (like I've gotten with maxwell 10gbit cards) should be clearable.
Unless you mean a separate internet connection entirely?