Ok, what I got so far about Pi-hole is that, in a nutshell, it acts as a DNS sever and uses a blacklist to filter DNS querries leading to ads, avoiding the add.
Maybe something implemented aeons ago or a stupid idea, but what came into my mind is the following: If one uses the same or maybe even a second blacklist which does not contain ads servers, but fake shops and other fraudulent websites, one could, just with using Pi-hole, essentially not only reduce the number of ads showing up, but also avoid landing on many fraudulent websites.
Is that an idea worth thinking about or stupid? If the latter, why?
Pi-hole just provides the filtering engine - you may fuel that with any kind of blocklists. There are lists out there that focus on malware and other threats.
That said, Pi-hole doesn't define itself as a security tool, for a reason:
While a DNS filter may contribute, it's incredibly easy to avoid DNS filtering, either by just using another DNS server, or by communicating to IP addresses directly.
For secure communications, you should primarily consider tools like perimeter firewalls and trusted computing, and add DNS filtering into that mix only as an addition.