I restore old Teletype machines, as I've mentioned before.[1] Keyboard feel on these is interesting. When you press a key, it locks down, the keyboard driveshaft rotates once, and the key releases. Then you can press another key. Effective typing has to be done in rhythm at 5 chars/sec, like playing a piano. You can't press two keys at once; once a key is down, no other key will move.
Because this was annoying to fast typists in the models from 1912 to 1926, in 1930 Teletype put spring-loaded keytops on their keys, allowing about 1/8" of spring loaded travel before you blunted your fingers because the key lever would not move yet. You could then start to press a key before the keyboard unlocked.
The IBM Selectric had one-character type-ahead in an entirely mechanical machine. That was a very nice piece of mechanical engineering. There are Selectrics with electrical I/O, but they are quite rare.