If you don’t know Faust, it’s an amazing programming language for creating digital musical instrument (and other audio doodads). It’s been around forever but doesn’t get the attention it deserves. It can create code for just about any platform you can think of (including Android and IOS). There is also an online IDE with literally hundreds of examples for all kinds of instruments and synths. The online IDE is not quite drag and drop but it’s easy to modify the examples and the output is a single file (for whatever platform you choose).
It is already possible to just tweak and example and download an .apk (or equivalent). But the focus is on the sound generation with absolutely minimal UI. There is virtually no way to (easily) add or change the UI or create any interesting interfaces. This is where combining it with Thunkable comes in.
Conceptually you’d just load the generated Faust file into Thunkable and a Thunkable would find the (very simple and intuitive) hooks. Imagine designing your own virtual instruments or synthesizers and creating visually exciting apps for them. I can imagine an explosion of Apple App Store and Google Play Store music apps.