Microsoft Remote Desktop Beta on Android versions 8.1.3 and 8.1.4 has now support with Remote Desktop Gateway and also you can Launch remote desktop connections from file or URLs.
The product with those features is still in beta, but there is a full blown supported RDP client for android available through Google Play – link.
The features are present in beta release and were described in the MSDN post by Eva Seydl.
Quote from the blog post:
Remote desktop gateway allows authorized users to connect to a remote computer on a private network from anywhere on the Internet. With the latest updates to the Remote Desktop Beta on Android, you can manage RD Gateways across remote desktop connections within the navigation drawer in the app settings.
Add remote resources to work with apps and desktops
Allows accessing remote app programs and session-based desktops (virtual desktops) that has been published by using RemoteApp and desktop connections feature.
We added a new option under the “+” button: Remote Resource Feed. A Remote Resources feed enables access to RemoteApp programs, session-based desktops, and virtual desktops published using RemoteApp and Desktop Connections. When you add a feed, you will find your apps and desktops under the respective tab in the connection center
The source can be found here.