HTTP3/Quic and TLS-passthrough

Hello everyone, this is my first post on the forum.
At first, thanks to everyone in the community for their efforts to run this project and the forum!

My question I think is a bit more theoretical than practical.
I am currently running a load-balancer in tls-passthrough mode. The certificates are stored only on the backend server and the load-balancer never terminates TLS session.
Proxy-Protocol is used to send the original source IP information to the clients.

Having started to learn something about how HTTP3/Quic connection are established, it was natural for me to start wondering if such a configuration could work also with HTTP3.

At first, is the new negotiation sequence compatible at all with such approach? The 0-RTT handshake would be possible in a tls-passthrough scenario?

And secondly, how can the proxy protocol be used to send the original source address to the backend server? Is proxy protocol already compatibile with UDP connection, or can it made compatible without much effort?
Does any webserver implenentation support ProxyProtocol for HTTP/3 or is working in that direction?

Thank you a lot for your interest in the topic!