I don't have the models memorized and I'm not at home to check, but I recently bought four towers that don't have TPM or a management engine and allow you to disable UEFI. They're not new, true, but they're certainly not 486 level.
> an Ethernet card with real Firmware in a real ROM, no platform controller, nothing. ...and a completely open BIOS w/o any binary blobs
None of which I was talking about. But I am pretty sure that with any motherboard, you can disable onboard Ethernet and install whatever adapter you want instead.