You should be able to use MITM capabilities of any HTTP/3-capable web server. I'd start by looking search for MITM configs of caddy, litespeed httpd, or nginx, all of which support HTTP/3 out of the box.
(I don't have experience with these tools / configs to make a suggestion, but I think this would work as a next step)
Author here, QUIC is a secure replacement for TCP that's also the basis of HTTP/3. I wrote this because I like to understand things at the byte level, and because (from past experience with my TLS 1.3 and 1.2 pages) it's a great way to remind myself of some detail of the protocol when I need it.
