So...what is the current state of the art for people who want to defend against endless ads, have a minimally invasive install relative to the users' current setup, have to tweak every device in, and not have to do more than say quarterly maintenance?

Every time I visit a non-technical friend's home I am absolutely horrified by what their tech experience has become. Browsing, oh my goodness. What a dumpster fire.

What system can I build for them that I can drop off with say 30 mins or less of setup to get going that isnt going to generate callbacks?

I'm thinking pihole (as DNS, with the user's home router tweaked to point clients there). Maybe running on a pi or a fanless pc. But perhaps there is something else?

Browser extensions are too complicated for very untechnical folks so maybe pass on those, although I am partial to privacybadger, ublock and of course a pw manager.