want to filter by regex on html title

Got kids, can't block youtube.com because we need it for other purposes too (educational, work).

But want to block certain things by regex on the html title, i.e. in the packet.  E.g. some video game names in HTML's title.

Sloppy is OK, doesn't have to be perfect.

Any ideas how to achieve that, on a router?

Don't want per machine or browser in the hone.  Can't admin all the machines two IT parents and several kids have.

I am longtime Netgear user with some IT admin and coding skills, would upgrade my WNDR to an open source WNDR if possible.  Would code a little bit.  Would use other solution too.