[...] Intel (and possibly other?) CPU's.
When the (nearly-confirmed) switch from Intel to ARM occurs, that's something to beware and investigate, as well. I forgot where I had read about it, but I think there was something similar on some ARM CPUs.
Also, for anyone who has an AMD-based Hackintosh (which only exists in Hackintosh form, as Apple never adopted their processors), there's their equivalent of Intel ME, called AMD Platform Security Processor (PSP), to beware.
The year cut-off is quite further ahead (2013), but it's still worth mentioning.
Note: Seems libreboot.org went offline today. Odd timing.
Google has it cached, though.
Outside of the Mac scope, for anyone interested in avoiding all the processor-level backdoors in future investments, there's the POWER9-based (PowerPC) Talos II, Talos II Lite and Blackbird by Raptor. On the less-expensive, but less-performant, x86/x64 front, computers that use the ASUS KGPE-D16 motherboard + a PSP-free AMD CPU (
"Interlagos" family recommended, see also
this). Those are the highest-end options for both architectures. (Note: for x86, Libreboot or, less-preferably, Coreboot is required for proper privacy on affected processors.)
Some websites sell the latter, like Technoethical. Raptor themselves sell the Talos family of computers.
If investing on the future of personal computing privacy, between the two options, it's better to buy a Talos family computer. (They are also absurdly powerful: the highest-end model is a 2-processor 44-core 196-thread computer (Talos II)! Lowest end is a single processor with 4 cores and 16 threads on Blackbird (some PC vendors would perhaps market that as "16-core"), which is still insanely powerful (120 MB of
L3 cache, anyone? PCIe 4.0?).