Also, the Teleharmonium, from 1907.[1] This was actually built. Startups with too much venture capital are not a new thing.
The Teleharmonium was the first musical synthesizer. The approach was to have one tone generator for each note, and switchgear run from a keyboard. That's a reasonable idea, and electric organs of the 1950s to 1970s worked that way.
But this was before amplifiers. They wanted to distribute the music over telephone wires to speakers in hotels, and needed power. So each tone generator was a sizable electrical generator. The whole installation was building-sized.
Here's the cover picture for the set, which few sources have.[2]
There's much similar material from 1900-1925. Some of which even worked.[3]
[1] https://commons.wikimedia.org/wiki/Category:France_in_XXI_Ce...
[2] https://www.le-livre.fr/photos/R15/R150145246.jpg
[3] http://120years.net/the-staccatonehugo-gernsbakgermany1923/