Add "PROXY protocol" Support -> quick win: DoH, DOT, DNSCrypt, Loadbalancing, dns rulesets with dnsdist

Unfortunately, dnsdist (or other proxies) is currently not very easy to use with pihole, because the pihole gui only shows the source IP of dnsdist.
Of course you can create a workaround with policy based routing (I don't think it works with dnsdist) but I would like to have an easier solution (I run everything with docker).

I thought XPF was the solution at first, but the proxy protocol is probably more common.

Unfortunately, a few things are still missing in order to make this work in the future.
My DoH setup:
Internet ---(HTTPS,443)---> Haproxy ---(HTTP,80, docker internal)---> dnsdist ---(dns,53, docker internal)---> pihole --(dns,53, docker internal)---> unbound

My DoT setup:
Internet ---(DoT,853)---> dnsdist ---(dns,53, docker internal)---> pihole --(dns,53, docker internal)---> unbound

Missing:
Haproxy ---(HTTP,80, docker internal)---> dnsdist. (only DoH)
- X-Forwarded-For support, only relevant if several services are to be used via port 443.
- dnsdist: dnsdist: DoH in reverse proxy: Accept HTTP Header for indicating real client (address) · Issue #8661 · PowerDNS/pdns · GitHub

dnsdist ---(dns,53, docker internal)---> pihole. (DoH and DoT)
- proxy protocol support
- dnsdist: Add support for Proxy Protocol between dnsdist and the recursor by rgacogne · Pull Request #8874 · PowerDNS/pdns · GitHub
- pihole: nothing found for the proxy protocol yet, therefore this post

Which service would have to be adapted for the proxy protocol for pihole, pihole-FTL or dnsmasq? Which service provides the DNS port 53 for the clients?