Ask HN: Certificate Literally for “Example.com”

I want to create some documentation for how to set up various servers with HTTPS. Can example.com be used for this? Assuming the reader has a private DNS server to point their clients to a self-hosted "example.com" domain, is there a public CA that offers certificates for example.com? Possibly with wildcards?

Answers to this question are difficult to google because a lot of documentation out there reads as though "example.com" is really just a placeholder (as it should be) for an actual privately owned domain.