@EmbraceTheGray You can just change DNS provider on your router settings to PiHole local ip address, this way you use DNS provider whichever you set your PiHole to use. You can set up dnscrypt-proxy with DoH on backend or other encryption for PiHole to use. More on tool here: https://github.com/DNSCrypt/dnscrypt-proxy
@EmbraceTheGray Just make sure that dnscrypt-proxy service listens on some other port than 53 because your PiHole uses it already, set some random port and specify it in PiHole DNS settings as 127.0.0.1:portnumber