Relevant information:
[meta] ECH (Encrypted Client Hello/ESNI)
https://bugzilla.mozilla.org/show_bug.cgi?id=1590863
Implement Encrypted Client Hello in NSS
https://bugzilla.mozilla.org/show_bug.cgi?id=1654332
Update ECH implementation to draft-09
https://bugzilla.mozilla.org/show_bug.cgi?id=1681585
Testing:
https://www.cloudflare.com/ssl/encrypted-sni
https://defo.ie/ech-check.php