"Subject has entered the website. Subject has 4 cores..." followed by a bunch of notes about my mouse moving around, or me making the window inactive.
Hardly terrifying.
The second link that follows that one (http://webkay.robinlinus.com/) really terrified me. I had no idea my private network hosts (192.168.X.X) or my private IP address could be scanned by a random webpage. Or the fact that the webpage could find out my laptop was charging with x% percent charge in real time, or the make and model of my machine and GPU. The geo location accuracy of my ip was also scarily accurate. All this when running in incognito with ad blockers. That is very close to being PII.
Add: https://github.com/straytachyon/dnsmasq_ad_block_script
Add2: You can even block select corp: https://github.com/jmdugan/blocklists