I’m interested in the same thing (both query upstream DNS over HTTPS servers, and answer to DoH queries), but using dnsmasq. I haven’t had much time to look into this yet, but will definitely try to implement it later, so any recommendations would be appreciated. So far my research notes on this topic only contain:

https://wiki.archlinux.org/index.php/Dnscrypt-proxy
https://packages.debian.org/sid/main/nss-tlsd
https://packages.debian.org/sid/main/tlslookup
https://blitiri.com.ar/git/r/dnss/b/master/t/f=README.md.html