I don't know what DreamFactory is, but in general, the cool newish (meaning anything since 1995) things will not work directly with Progress, though some of them might work in terms of Progress being capable of impersonating a SQL database, sort of, and some of them (Git for example) are basically language-agnostic to begin with.
However you can certainly "setup API calls", though, the same way (roughly) as you can in almost any other languages, with REST or SOAP or native proxies (Java, C#) or sockets and probably a few other ways that I'm forgetting. So if DreamFactory knows about REST, you could hook it up to Progress, but you'd still most likely need to do a bunch of stuff in Progress to make that happen.
If all you do right now is a Progress DB with a Progress GUI (which I am guessing could be true based on the way you phrased your question), you might need to branch out into the world of AppServers and adapters and AIA and Tomcat and so on, which is a joyful world, but quite a large and complex one.
