The real argument for using stenotype keyboards for coding is not typing speed, it's avoiding RSI. On a stenotype keyboard you "type" chords by pushing down with your arms, not your fingers - it's a bit like playing an organ, or a synth keyboard. You don't hear about many organists getting RSI (though some piano players do). The fingers also just move a lot less, much of the "moving" to different keys is also done with the arm muscles.

I agree w/ others in this thread about the underlying challenges for using a steno keyboard for coding. You basically need to pick a custom chord for every program identifier, keyword or symbol, and somehow make those chords memorable. Perhaps a custom IDE featureset can help, leveraging the LSP or tree-sitter parsers?