Not recommending that everyone try to learn this, but Wolfram has rigged up a laptop so that he can walk and work at the same time (scroll down to the photo of him w/ a hat in the woods and a walking desk to see what I mean):
https://writings.stephenwolfram.com/2019/02/seeking-the-prod...
Half of it has.
Chorded keyboards are great, head mounted displays are still meh, but a typical smartphone is a wonderful display to strap to yourself.
Shameless plug: https://github.com/andrey-utkin/wearable-computer/
How fast can you type with it? Can it be easily used for key-combinations using modifier keys and such?
I'd say it's OK. It's not even remotely on par with typing speed on laptop-size keyboard, but I'd say it provides a reasonable trade-off. And it has enough keys to use desktop software without much pain one way or another.