Parental filters

Hey guys,

Hope you're all doing well staying in, I'm having a hard time myself though.

Anyway, we have been tasked with the following;

Parental filters for individual clients (pppoe/static)

As I understand it, these are usually done with a firewall where you block it for everybody or for a specific IP. Though that is something an admin would do, not the parent.

We don't have a conventional firewall, so that's out of the question.

Here is what I'm thinking and I don't know how they would get done though but it can be done with DNS.

Setup multiple DNS with pi-hole and one with Google. Google blocks nothing. One blocks porn, one blocks gambling sites and so on. Since it's mostly pppoe, we will have to automate it somehow.

Is there any other way of doing this that might be reasonable for 20k clients?