This is called a chorded keyboard [1]. Like seemingly everything invented in the following 40 years, it was introduced by Douglas Englebart in the Mother of all Demos in 1968. Englebart had a iOS app that allowed you to chord type as well. 1. https://en.wikipedia.org/wiki/Chorded_keyboard
Douglas Englebart is the proof to me that even if you could go back in time, it isn't necessarily true that you could leverage your knowledge of future technology. Poor guy messed up the timeline so much that even his stock market knowledge was useless!
Relatedly:
"Don't worry about people stealing your ideas. If your ideas are any good, you'll have to ram them down people's throats." -- Howard H. Aiken