A great survey--nice to see Delia Derbyshire getting some credit.

Other pioneers about the same time as Perrey: Otto Luening & Vladimir Ussachevsky https://finderskeepersrecords.bandcamp.com/album/tape-recorder-music

and Jim Fassett ("Symphony of the Birds"; "Strange to Your Ears").

And as far as pop music goes, let's not forget the masters of the theremin leg (1969): https://youtu.be/q_sRkHwSxcI