I have pretty much given up on Arduino. They had me almost interested again when they announced the Pro IDE, but several months later they still haven't put the source code on Github: https://github.com/arduino/arduino-pro-ide

I am not interested in the Electron-based IDE, but they seem to be using the Clang language server, which is perfect for integrating with Emacs. I have been sitting here for months ready to hack on this stuff and make it work perfectly, but all I have to work with is the raw source files contained in the Electron bundle with no license, so I've basically given up. Once again, the Arduino team is doing Weird Stuff with software, and this whole Pro thing feels like "the joys of working with Broadcom, but we stick random Open Source logos on thing without actually being Open Source".

I have a lot of microcontroller projects I want to do, but without modern development tools, it's not worth it. They are so close... just let me hack on your source code, please. I'll do it for free and you can do whatever you want with the code. But they don't seem to want to play ball.

(Recently I have been playing with Tinygo, but I am still not motivated because "go doc", my favorite go tool, and gopls don't work... and I'm not quite sure that it's worth the effort to make work yet. My toy tinygo projects have gone pretty well, though, so maybe it is worth making their IDE support work, and forgetting Arduino ever existed. I feel like Circuit Python / Micropython is the path of least resistance right now.)