Surprised not to see a mention of Talos II system based on IBM POWER9 technology that is open spec and otherwise a very competent build with fully open hardware FPGA mainboard and stuff like physical trip jumper protection, and potential for customised security measures via the BMC, Arctic Tern, et cetera. IBM is notoriously good at virtualisation, and POWER9 is very competent for machine learning workloads, the 2U and 4U systems they offer can go up something ridiculous like 176 threads in a two-socket configuration and there's plenty of lanes. You can reprogram the firmware, too; it's all out there in the open and you normally wouldn't need special hardware.
This is like the third time I'm hearing about these raptors in the past month and I want one. I want the $10,000 one. Your comment is the most constructive one in this thread, because it sounds like the solution for all the concerns expressed above has finally arrived. Who here is willing to put their money where their values are?
In reality none of the "privacy freaks" will ever purchase one, I've recommended these to various privacy-minded people I know and the majority either (1) can't see past the fact that it's IBM hardware (not hip), or (2) make up excuses the like of "DO YOU REALLY believe IBM would do a system without a backdoor? A system with a starting price of $5,500— it must be a rip-off, not good enough a deal for me!" I know there's plenty of nice and horrible people in everything but honestly if I got two bob a piece for every FOSS cheapskate I've encountered is too similar to one another for me _not_ to attribute this to cheapskate mindset. People who are saying things like "Mac is a rip-off!!! bad deal, Intel better performance" all the while being clueless on power consumption, for example. It's much cheaper to just say something seemingly profound like "There is no true privacy, we're all pwned by NSA!!" than to purchase and actively integrate an expensive RISC ISA system based on free hardware into your workflow... A the end of the day, we only have ourselves to blame.
You can get one for not less than $5,500. https://www.raptorcs.com/content/TLSDS3/intro.html