They provided a list of the CPUs they tested on from K8 (2013) to Zen 2 (2019). Looks like they only provided benchmark data for a couple. They did indeed use Linux as it is the preferred O/S for this type of research. All the previous vulnerabilities have used Linux for the proof of concept. I agree that these are mostly of academic interest and are of little concern to the home user. But equally they are not faked or the work of Intel shills.