The original chording keyboard was from Baudot, around 1897.[1] The original plan was for the sender to send 5-bit teletype characters with a 5-bit keyboard.
This was deployed, not just a prototype.
Early versions had to be mechanically synced at the sending and receiving side. The typists had strict timings so the other end could receive it. This led to a version of punch cards that could be pre-typed and then fed in automatically, reducing the skill needed of the operator. The linage to teletypes were almost obvious.
The form of a keyboard had to be invented. Early printing telegraphs used a piano-like keyboard, with white and black keys.[1]
(Keeping both ends in sync was a huge problem. The machine shown was synched by having the sending operator send AAAAAAAAA while the receiving operator made adjustments. If the machines got out of sync, the receiving operator opened the line switch, which stopped local echo at the sending end. Then both ends had to repeat the AAAAAAAAA drill.
It took a long time, from 1846 to 1907, until Howard Krum finally came up with a mechanism that didn't have sync problems. Krum had the advantage that steel and stamping were available. The clock industry had figured out how to mass-produce mechanisms. Mechanism design then got out of the handmade brass era. This was, in its day, an advance comparable to going from tubes to ICs.)
[1] https://collection.sciencemuseumgroup.org.uk/objects/co33197...