HTTP/3 support is a bit frustrating, since it's highlighted a serious split in engineering effort & focus, which has created a two-tier internet: browsers & big CDNs do support and use HTTP/3 heavily, but most small tools, servers and programming languages don't have stable built-in support at all (e.g. no support in the standard libraries for Go, Node.js, Python, etc) for either clients or servers. Even big tools like Nginx only have experimental support, disabled by default: https://nginx.org/en/docs/http/ngx_http_v3_module.html

Many years after this article was posted, OpenSSL does now have QUIC _client_ support (from 3.2: https://github.com/openssl/openssl/blob/master/README-QUIC.m...) but server support is still not available (and for Node at least, OpenSSL's approach here has been one of the main blockers for serious built-in HTTP/3 support).

There are some native libraries you can use to work around this, but they're not easy to set up in many cases and they're totally separate from each languages normal network stack. As a typical developer, the general solution is still 'just use HTTP/2 everywhere', even as HTTP/3 use on the browser web spikes higher and higher.