Please explain in more detail what is special about the hexadecimal IPs. Also, please keep in mind that Pi-hole operates as a DNS server, i.e. we can only block requests to domain names, not IP addresses.
No, the underlying DNS server dnsmasq does not support Regex evaluation. You can either exactly block domains (e.g. something.else.com) or wildcard block domains (incl. all of their subdomains).
No I mean urls like this 8baf7ae42000024 .com and 8777446132e88e1f3 .com, these will show up as unreachable or some other error unless they have /afu= or some other subdomain after the domain name. They come from an anonymizer site called www.pananames.com and domains-anonymizer.com, got it from using https://dig.whois.com.au/whois/8777446132e88e1f3.com
They change usually within a day or two and there are a couple of sites that offer this kind of anonymizing. Some sites use these to load scripts that bounce you around before landing you on a fake malware warning page or some other ad page
edit Looking back I realised that url is correct and not IP