[Disclosure: I’m the OpenSSL Foundation community manager as of January.]
As it turns out, OpenSSL 3.5 is slated to be released in April with QUIC server support. There is also a demo of an HTTP3 server that uses the OpenSSL QUIC API with nghttp3.
(Since the issue of governance was raised in that link, I should point out that OpenSSL adopted a new governance structure last year. I’m cautiously optimistic and I do think it helped get QUIC out the door at last.)
It appears nginx will adopt OpenSSL’s QUIC API. No indication of the timeline yet, however.