Hoi Andres,
Super interesting, I appreciate the effort! One thing I noticed when you wrote "2.7% (4'394) are internationalized domain name (IDN) using Punycode", I think that N-count is higher than 4'394.
I'm pretty surprised that of the 1.7M domains with an MX record, only 57% have DKIM -- do these folks ever send e-mail to yahoo/gmx/gmail/office365 ? As a DKIM/DPF/DMARC/STS-MTA user, for now I can still deliver mail to Big Tech, and I hope to be in that state for a long time to come (not only because my mailserver is older than most of Big Tech ...).
Thank you for sending along.
groet,
Pim