FWIW - I found it fairly trivial to set up CloudFront in front of my buckets [1], so that I can use HTTPS with AWS Cert Mgr (ACM) to serve our s3 sites on https://mydomain.com [2].
I set this up some time ago using our domain name and ACM, and I don't think I will need to change anything in light of this announcement.
1 - https://docs.aws.amazon.com/AmazonS3/latest/dev/website-host...
2 - https://docs.aws.amazon.com/acm/latest/userguide/acm-overvie...