[grackle2]

It doesn't really run an OS like you may be used to. It runs FreeRTOS, which schedules tasks. One of the tasks is running Micropython. (Other tasks are for audio, the display, MIDI, touchscreen, the sequencer, etc). There's no BIOS-level code to use, we have to manage our own screen (including drawing in groups of scanlines at a time to save RAM.)

Yes, you can use this to make synths. It's powered by our own AMY under the hood, which is a low level oscillator bank with a LOT of features https://github.com/shorepine/amy . And then you manage them in Python, including MIDI, note stealing, polyphony, sequencer, etc. See more here: https://github.com/shorepine/tulipcc/blob/main/docs/music.md

You can NOT do audio input effects -- there's no audio input. You can load samples from WAV files and play them back.