In the not so distant future, people will begin turning their houses into faraday cages to ensure nothing can access the outside unless given proper permission.

This is the way.

So I did some looking, and as far as I can tell, there's no definitive proof of someone testing this and reporting on it. It might just be all rumors and speculation.

Ah, gotcha. That would seem like overkill if that's what would be needed.

That would only work until your neighbor leaves their guest WiFi open.

AdGuard as a service is alright, but it’s essentially just a pihole that you don’t have any control over. It does DNS level blocking, which means the ads get blocked before they even load on your network.

The issue is that since you’re routing all of your DNS traffic through AdGuard, you’re directly telling AdGuard which sites you are using. So there are concerns that you are just shifting the data collection from the ad companies to AdGuard instead, but AdGuard has the ability to be way more invasive in how the collect data.

Just set up dual piholes (one for your primary DNS, and one for your secondary DNS) instead. You get the exact same end result, without any of the data collection worry.

Mikrotik are really aimed at advanced users, ubiquiti brand themselves as prosumer products. I found the Ubiquiti interface a complete mess - but it could just be me.

If it can run OpenWRT I'd suggest taking that path (if you like to tinker / the device supports it). My Google WiFi hubs are still humming away after all these years - now with way more features and a usable interface!