In order to measure reaction time, use the perf_counter function from the time module. This function requires no arguments and returns a floating point number of seconds. The number of seconds returned has no specific reference point, however the difference between the number of seconds returned by two different calls to perf_counter can be used to find the number of seconds that has passed between the two calls.
To use perf_counter, update the import at the top of your file to include perf_counter.
from time import perf_counter, sleepAbove the button_pressed function and below where you setup the LED and buttons, add a variable named start_time and set it's value to zero.
Immediately before your program turns off the LED, store the return value of the perf_counter function in start_time.
In the button_pressed function, and add a variable named end_time and assign it the return value of the perf_counter function. This line should come as early as possible in the function so that you stop timing as soon as possible, and are not including the time your code takes to run in the reaction time.
Update the button_pressed function to calculate the reaction time of the winning player using start_time and end_time, and print out the calculated reaction time for the winning player.
Before going further, make sure that your reaction time code is working. Run your program and push each button when the LED turns off. Make sure that the correct player and a reasonably accurate reaction time is printed when you push the button.
If the buttons don't do what you expect them to, there may be a problem in your circuit or code. Identify and fix any problems, then run your program again to check if the problem has been fixed.