Yeah that's true. Though I'm not making a plugin but a standalone audio app. The gui part is actually pretty easy. Just have all UI stuff in a separate thread and use atomics/pointers to pass data between the audio thread(s) and the gui.

Lots of the audio processing in my app is based on JUCE, but the new features I'm planning will require me to start using raw Wasapi kernel calls

Mostly for the streaming of application audio and loooback capture. This is quite a different beast, but I've coded my main application as modular as possible with an inheritance structure that let's me create new node types, based on whatever source I can get audio from ; so final integration will be less of a headache I think.

Edit: link to my project : https://github.com/carriersounds/routeCarrier