How would you like to expand the functionalities?
Ability to generate and use certs directly for the existing server

Are there alternatives?

• Alternative is to use express app included in htttps-localhost but it cannot be used in cases like socket since app.listen won't work.
  https://socket.io/docs/#Using-with-Express
• Another alternative is to use mkcert directly to generate the cert. This is an extra step to download the certs whereas https-localhost does that automatically and developer doesn't have to run commands for that

Is it a breaking change?
Probably yes, depending upon what would be resulting API when this feature is implemented