Small addition to this: the closest CPU Intel sells that matches the Mac Pro spec is the Xeon Gold 6144 ( only supports 48 PCI-E lanes, though). The clue is that Apple's specs list 24.75 MB L3 cache, which the Xeon Gold 6144 matches, while the Xeon W-2145 listed by Linus only has 11 MB L3 cache.
That CPU is also ~$3,000 in price, i.e. ~$1,800 higher than the one listed in the video, bringing the "self-build" price up to $4,960 (instead of ~$3,160 as in the video), meaning the "Apple tax" is actually down to around $1K.
The machine is a lot "less" overpriced for the parts than people say - it's just a questionable base configuration as they picked one of Intel's most overpriced Xeon chips as baseline. And the price for the stand is still silly, of course.