Looks like the interface is created by Qt5.
I’ve done some work with PyQt, and I like it a lot. Qt is a very powerful cross-platform GUI toolkit.
When Audacity was first created, WxWidgets was chosen as the cross-platform GUI toolkit as there were doubts about the license terms of Qt at that time. Qt now has a clear dual licensing model, suitable for open source (free license) or closed source (commercial license) projects. Audacity is heavily integrated with WxWidgets and is unlikely to switch to Qt as that would require a massive rewrite of hundreds of thousands on lines of code.
I have seen an experimental version of Audacity with a much simplified touch screen interface. Unfortunately the developer of that feature has not been engaged in Audacity development for over three years, and as far as I’m aware he never released the source code. So yes it is possible to make a custom touch screen interface, but it’s not an area of current development.
I expect that you find Audacity difficult to work with for “real-time” production. From the very start, Audacity was designed as a “post production” (paste it together later) type of application, so everything is designed that way. If you need to handle multiple streams simultaneously, you may be better to design something from the ground up (there are high level audio libraries available for Python, and Qt can massively simplify the development on nice, cross-platform GUIs).
There is some developer interest in developing a HTML5 interface, and some preparatory work has begun on that, but it’s a long way off before anything usable will be available.
There’s some information about what is coming soon in the new scripting interface here: https://alphamanual.audacityteam.org/man/Scripting_Reference