Does pro not have the “domain join instead” option in OOBE anymore? It definitely used to, and Enterprise does.

I don’t understand how you’d domain join otherwise.

Pro doesn't have an option to join a domain in the default OOBE. I think that went away in some iteration of 10.

Pro definitely doesn't because the above procedure is what I always have to do to get joined to a domain without creating or using a Microsoft Account. (And then I've got a local account to clean up.)

I don't think this is the way it should be, but just to answer your question, you'd go through the normal setup for a single user PC, then join AD in the Settings app.