additional proxy to filter ads (privoxy?)

Basically I bring back Privoxy out-of-scope/not planned? - #3 by DanSchaper for two reasons:

  1. Pi 4 is out and fast enough to do the job
  2. pi-hole does not need to run on a pi - mine is running from docker on my NAS.

So there are scenarios when this makes perfect sense and it would be a great feature.
Also it would be enough to filter just some domains like e.g. youtube.
A squid + squidguard + privoxy might make the most sense - also for performance.
See: http://www.ucci.it/docs/ICTSecurity-2004-27.pdf

Please consider adding this.
If there is a project already doing so - please add a link.