More then an "issue" this is a question.
Reading the file https://github.com/nginx-modules/docker-nginx-boringssl/blob/master/mainline/alpine/Dockerfile in the parameters for configure of ngnix the --with-openssl-opt=enable-tls1_3 is missed.
Is it OK build nginx without --with-openssl-opt=enable-tls1_3?
In nginx the TLS 1.3 will works also if the option --with-openssl-opt=enable-tls1_3 is missed?
Thanks.