Thank you. Now it's working!!!
I add this rule to
/etc/udev/rules.d/99-input.rules
SUBSYSTEM=="input", ATTRS{name}=="button*", MODE="0660", ENV{ID_INPUT_KEY}="1", ENV{ID_INPUT_KEYBOARD}="1"
And now have GPIO key ID_INPUT_KEYBOARD parameter too.
pi@retropie:~ $ udevadm info --query all /dev/input/event1
P: /devices/platform/button@1a/input/input1/event1
N: input/event1
L: 0
S: input/by-path/platform-button@1a-event
E: DEVPATH=/devices/platform/button@1a/input/input1/event1
E: DEVNAME=/dev/input/event1
E: MAJOR=13
E: MINOR=65
E: SUBSYSTEM=input
E: USEC_INITIALIZED=28281822
E: ID_INPUT=1
E: ID_INPUT_KEY=1
E: ID_PATH=platform-button@1a
E: ID_PATH_TAG=platform-button_1a
E: LIBINPUT_DEVICE_GROUP=19/1/1:gpio-keys
E: ID_INPUT_KEYBOARD=1
E: DEVLINKS=/dev/input/by-path/platform-button@1a-event
E: TAGS=:power-switch:
Bidding hotkey to GPIO key is now working.
