[Answered ]-Add SSL to AWS elastic beanstalk public DNS

does EB’s public domain considered good enough?

Sadly, its not enough, because this domain belongs to AWS, not you. You can only get valid public SSL certificates for domains that you own or at least control. This means, that you can’t get SSL cert for EB default domain.

You can add CloudFront in front of your EB and this will give you https endpoint. But all traffic between CloudFront and EB will be http (not https), because again you do not have valid SSL certificate for EB.