Look at CommandFusion's product iViewer and their companion guiDesigner. iViewer is the run-time and runs on iPads, iPhone and Androids. GuiDesigner is the development environment (think Pronto Edit). The product is based on the Google V8 Javascript engine. If you were using prontoScript it should be easy to get aboard.

I have been able to do anything I want because of the product being based on Javascript. Although they have a "native" system which does not require Javascript knowledge, the possibilities become endless once you decide to go the Javascript route.

Aside from voice control (Amazon echo's) my homes GUI is wall mounted iPads running iViewer. The central control computer as a Raspberry PI.

The command Fusion product is well documented, and is supported by a good responsive forum for help.