That said, if you're using a wireless keyboard it's pretty much a given that the keystrokes can be recovered by timing analysis regardless of the manner of wireless connection. At least unless you happen to hunt and peck painfully slowly.
Embedded touch is a whole'nuther issue. One could certainly remotely measure the radiated emissions of a cell-phone to get finger proximity and position in at least one if not both XY dimensions.
My father worked in defense. He shared lore about the genesis of tempest, the requirement to use faraday cages to protect secrets, gear, etc.
The story goes that some kind of red team set up shop down the road from some missile tests (or something) with some simple gear. Afterwards, they shared the launch codes used, shocking all the brass. Hence the need for shielded comms.