[samueloph]

> edit: even curl itself - which created the original document linked above - has http 3 just in an experimental build.

It's not experimental when built with ngtcp2, which is what you will get on distros like Debian 13-backports (plain Debian 13 uses OpenSSL-QUIC), Debian 14 and onward, Arch Linux and Gentoo.

Reference: https://curl.se/docs/http3.html