content: This is changing the transport mechanism. So a PiHole would not be able to see/filter DNS requests since they would originate from the browser and would return to the browser. Simply turning on browser DoH locally with a PiHole in the network would either break DNS or bypass the PiHole. The correct implementation would be for the PiHole to run DoH to provide transport encryption, and the local browsers to still rely on the PiHole. Then you have domain scrubbing/ad blocking plus transport encryption.  I am sure the PiHole will be upgraded to support DoH. This is basically Option 3 that SithEmpire is talking about in the top comment...OS + DoH.