First of all; to support a new provider it must have a (public) API. Next, this being an open source project with volunteers, someone must be willing to invest the time required to implement it in rclone. In general: Unless you can do it yourself, or can find someone who are willing to do it for you, maybe hire/sponsor a developer, it's not very likely, I'm afraid.. There are currently 63 open tickets on GitHub regarding new backends, including:
In case you're on Windows have a look at AirExlorer(.net).
Though not as good/versatile as rclone it's still way better than WebUI and provides a nice explorer-like interface to Degoo and Mediafire.
Free version provides 2 concurrent up-/downloads, encryption of paid version does not work for at least Degoo (didn't try Mediafire).
