Purpose
A DNS service is like a phonebook for internet queries. By filtering out specific domains before the content ever reaches your device you can completely avoid seeing advertisements, loading frivolous content, or enact child controls. Most importantly, it does not require specific software, hardware, or operating systems to function, which means it can be used for almost any device on the local network.
This was an idea originally inspired by Aidan Capaldi
Tutorial I used Documentation rPi Portal DoH and filtering discussion Hardcoded DNS fixes