Used OpenCompute enterprise server from eBay, with LinuxBoot as BIOS.
Future: OpenCompute platform based on OpenPower CPU, Open System Firmware and an open-hardware implementation of Microsoft Cerberus / Google OpenTitan.
https://store.vikings.net/libre-friendly-hardware/the-server...
How far along are these Open Architecture Systems?
An alternative to me_cleaner on some systems (like ThinkPad X200) is to replace the BIOS entirely with Coreboot [1]. More recently, it was found that me_cleaner appears to let you remove/disable all or part of Intel ME on those and some other architectures but still boot.
[1] My own notes from when I played with this, which was a mixed success (it was way too much headache to have a huge number of people each do): https://www.neilvandyke.org/coreboot/