Fun fact: they've been available for over a decade at this point. I wouldn't be surprised if it goes back a few years more than this 2008 article. Never personally used one, though.

https://www.geeky-gadgets.com/geeky-gadgets-the-bluetooth-la...

Ain't great. You can only type certain keys at a time since the beam-break for j prevents a follow-up n in the denounce period. I only get about 30wpm... Disregarding feedback.

It could probably be done now just by looking at hand shapes and if you’re a touch typist you might not even need the projection, just a dot or two (which could just be stickers on a surface) to orientate your hands over nothing.

Hand shapes for typing are far from standardized or recognisable. Nowhere near the accuracy a laser beam break gives you. (The projection LED is separate from the detection laser, which is much lower power)