I've tried ChromeOS Flex on all kinds of gear. It just works.

Probably the same reason why only newer than 8000 series Intel CPUs are officially supported for Windows 11.

It's the "easiest" way to ensure TPM 2.0 compatibility, at a CPU family level of granularity. (Yes, there are 7000 series with TPM 2.0 support, but I believe that may have been the exception to the rule)

Edit: I took a look at the certified list and noticed that I indeed, cannot read.