The m8 and the recently, heavily promoted Woovebox 2 are the Emacs/Vim of grooveboxes. They hide a vast amount of functionality behind what initially seems like an impenetrable jungle of button presses and shortcuts; a system that ultimately proves* to be highly ergonomic.

*Based on what I read. Sadly, I don't own these devices.

I own an M8 (and also, happen to be a vim user lol) and it's sorta true, but it feels a lot more natural if you're familiar with the LSDJ-style workflow. LSDJ is a DAW built for the GameBoy so was working with very constrained hardware. Both are derived from sequencer workflows, but I'm not quite sure which or where those originated.

That being said, the M8 workflow isn't all that bad, but it's definitely less visual than most other DAWs.

Yeah I'm not an expert by any means but my understanding is the Teensy 4.1 is especially ideal for DIY synths between the number of pins available and its strengths as an audio processor.