For blocking YouTube ads, I cannot recommend Vinegar more. It’s a safari extension that replaces the default YouTube player with a standard HTML5 video tag. Which means all the functionality of iOS videos (PiP, backgrounding, scrubbing) and no ads.
Is there an ELI5 for what NextDNS is/does? I downloaded and enabled it because I see it recommended often enough, but I have no idea what it does for me or if there's anything else I need to be doing with it.
NextDNS is a privacy respecting DNS service. You can learn more HERE. If you’re unable to self host your own PiHole or Adguard Home, it’s the next best option.
Even if you are able to self host Pi-hole or AGH, NextDNS is a great option because you can use it even when you're not at home. I use it on all of my mobile devices.