random number generator 10-side dice alternative
One problem is that keyboard keys may or may not be uniform. Look at the F and J keys - they may have a little dot of plastic to identify them with your fingertips. That little dot may make them heavier or lighter than other keys, affecting how they shake up in a hat. Some keyboards, like Das Keyboard, were built with different spring actions for different keys, which might or might not affect the weight or shape of each key. And some keyboards have larger curvatures for various key tops, and those keys definitely have different mass.

The problem is that creating perfectly symmetric keys is not a design goal for keyboard designers, so without studying and measuring each keyboard, you won't have assurance that any particular keyboard is suitably random for your purpose.

They may also be just fine if you are not looking to generate thousands of passwords. If you're concerned, though, consider repurposing a device designed to generate random values. A bingo cage could be refilled with 26 hand lettered balls. Playing cards could have handwritten letters and shuffled extensively. A 100-sided dice could be repainted to match your character set, and extra values blacked out to indicate "roll again".

See also "diceware" for a way to turn 6 sided dice into passwords.