marioz
1
I cannot add züripeople.ch as a custom domain to a Pages project - the error says “Please enter a valid domain.”
I successfully added the very same apex under the Websites section.
marioz
2
I solved it by adding the custom domain as “xn–zripeople-q9a.ch”.
I don’t know yet how the these special characters work but this does it 
marioz
4
It’s all about punycode:
https://www.charset.org/punycode