But this does not work on MacOs 13, 14 and 15:

import os
cmd = 'open -a KeyboardViewer'
os.system(cmd)

I had to use the following apple script can do this:

tell application "System Settings"
    activate
end tell

do shell script "open 'x-apple.systempreferences:com.apple.preference.universalaccess?Keyboard'"

set endDate to (current date) + 5.0
repeat
    try
        tell application "System Events"
            click checkbox 1 of group 3 of scroll area 1 of group 1 of group 2 of splitter group 1 of group 1 of window "Keyboard" of application process "System Settings"
        end tell
        exit repeat
    on error errorMessage
        if ((current date) > endDate) then
            error errorMessage
        end if
    end try
end repeat

tell application "System Settings"
    quit
end tell

I wonder if there is an easier way to do this. I would be too much grateful for any help!