Yes KEY? was recently added. It needs a kernel_kbhit routine that flags when a key is available. More in the
platform README.
As Sam suggested you can use it in a loop to time the keypress as a random seed, e.g. : foo 0 begin 1+ key? until key ;
You might also be interested in the bundled c65 monitor/debugger which is an alternative to py65mon which is about 100x faster and includes heatmap profiling.
BTW, it's a nice full circle moment since it was reading about Planck that originally led me to explore TaliForth!