It should be completely transparent; unfortunately, there are way too many networks with firewalls configured to only allow known ports of known protocols, inst

It should be completely transparent; unfortunately, there are way too many networks with firewalls configured to only allow known ports of known protocols, instead of following the design principle that only the end hosts should care about layers above IPv4 and IPv6. Since QUIC and HTTP/3 uses UDP instead of TCP, these firewalls will drop or reject the connection. That is: any network that is capable of handling traditional HTTP is capable of handling HTTP/3, but many are explicitly configured to not do so.