Why isn't there a commercial Pi-Hole product?

I think the problem wouldn't be the software itself (that's just a DNS proxy) but maintenance of the block lists. The lists used by pihole by default are decent but do cause problems at times, either intermittently [0] [1] or persistently (for example there's a certain cookie consent banner embed that gets blocked, and some sites embed a script for it in such a way that the site is unusable when the script can't load, a scenario for which the block list's maintainer has no sympathy [2]).

When someone decides to pay for SaaS instead of installing their own instance, unless implementation/maintenance is difficult (and I'd argue it's not difficult in the case of running PiHole), that money is for support. But this would be a support nightmare.

Also, typical SaaS runs over HTTP and has a GUI that can do user authentication, so that access is gated by payment. PiHole runs over DNS protocol, which has no such authentication gate that I'm aware of, so if you stood up a resolver (akin to 8.8.8.8 or 1.1.1.1 but with ad filtering) it would be open to the whole world with no payment required. It would instead need to be an appliance the user puts on their own network (or flashes onto their router, or whatever), and anyone willing to do that would probably be willing to run PiHole for free instead.

[0] https://github.com/StevenBlack/hosts/issues/2514#issuecommen...

[1] https://github.com/StevenBlack/hosts/issues/2515#issuecommen...

[2] https://github.com/StevenBlack/hosts/issues/2257#issuecommen...