Nginx has support TLS 1.3 early data with OpenSSL 1.1.1 and BoringSSL started from 1.15.3/4 - http://nginx.org/en/CHANGES
current pagespeed alpine image use libressl What next direction? - wait LibreSSL - switch to OpenSSL ( https://pkgs.alpinelinux.org/packages?name=openssl1.1&branch=edge&repo=testing&arch=x86_64 ) - build with BoringSSL?
