Normally Switch homebrew means C/C++ and the devkitPro toolchain. Brewser makes the Switch run web apps instead: HTML/JS/WebGL from a curated catalogue. If you can build a web page, you can build a Switch app, and the same app runs on PC and phone too.
As for MIDI, the homebrew answer is...
Hi everyone - after a few months of work I'm releasing Brewser, a web runtime and app platform for the Switch.
What it is
A real browser-grade engine — V8 with JIT, Skia rendering, WebGL1/2 via Mesa — running as standard homebrew. Advanced Three.js scenes work, first Unity WebGL content runs...