Test code
(global-set-key (kbd "<KEYCODE_X>")
(lambda () (interactive) (execute-kbd-macro (kbd "M-x"))))
(global-set-key (kbd "C-<space>") #'set-mark-command)
(global-set-key (kbd "<KEYCODE_X>")
(lambda () (interactive) (execute-kbd-macro (kbd "M-x"))))
(global-set-key (kbd "C-<space>") #'set-mark-command)