Are you sure? When I type https://xn--971h.com in it doesn't work, but clicking the link in your comment does because HN has made the href x.com. The browser converts π.com to x.com before going there too. Moreover, X and π are treated as equivalent characters in this context, so whois π.com looks up x.com, and π.com's punycode encoding is x.com: https://www.whatsmydns.net/idn-punycode-converter?q=%F0%9D%9...
whois xn--971h.com returns the same thing as an unregistered domain.
whois xn--971h.com returns the same thing as an unregistered domain.