I try to elaborate on my previous post:
The whole WHOIS protocol lacks proper standardisation, e.g. it does not guide encoding at all -neither for queries nor for the requested content- which would be a prerequisite for internationalisation, many of the data are not required to be well-formed (e.g. data might be labeled differently by different providers or not have the same semantics tied to it), there is no standard for determining the authoritative WHOIS server for a given domain name, possibly leaving you with no or incomplete information, etc.
(Just do a whois on google.com
and heise.de
to get an idea of what I am talking about, and mind that output would also differ by the whois binary in use.)
Worse still, to my knowledge, access to the data you wish to scrutinize here is currently not standardized at all, nor are registrars obliged to offer programmatical access to that data for free (afaik, only mailing and email address as well as phone number are required to be publically available - but subject to be adopted to latest GDPR requirements).
They also commonly enforce rate limits on the amount of queries they would allow from an IP address, or may offer to lift such limits for a fee.
As accessing and correctly extracting or interpreting that data is tricky, numerous service providers have established a business around this by offering access to well-formed proprietary APIs.
So rather than wasting resources on redeveloping something that is already available, Pi-hole offering integration with one of those APIs could be an option.
However, employing such a service would require you to enter a contract with the provider of your choice (e.g. 50 bucks for requesting max 24k domains - per month, that is).
And then there may be additional contractual obligations, e.g. no permission to store requested data locally, which would restrict you from caching data over a prolongued period, that in return would have to be honored by Pi-hole in order to not make you transgress those obligations.
All of this to block you from accessing the website your friend has just started when opening her new cafe?
Why just block new domains? And why suddenly allow them after some 30 days? I doubt that 'new' domains are any more or less trustworthy than existing ones (avoiding having to define the exact meaning of 'new') or -if they are malevolent- that they would cease being so after an arbitrary period of time.
When operating at that level of confidence or mistrust, maybe employing a deny all strategy would be worth considering, and certainly easier to implement.