zmk/app/boards/native_posix.overlay

#include <dt-bindings/zmk/keys.h>
#include <zmk/kscan-mock.h>

/ {
	chosen {
		zmk,kscan = &kscan0;
		zmk,keymap = &keymap0;
	};

	kscan0: kscan_0 {
		compatible = "zmk,kscan-composite";
		label = "KSCAN_COMP";
		rows = <2>;
		columns = <4>;

		left: left {
			kscan = <&left_hand>;
		};

		right: right {
			kscan = <&right_hand>;
			column-offset = <2>;
		};
	};

	left_hand: kscan_1 {
		compatible = "zmk,kscan-mock";
		label = "KSCAN_LEFT";

		rows = <2>;
		columns = <2>;
		events = <ZMK_MOCK_PRESS(0,1,300) ZMK_MOCK_PRESS(0,0,300) ZMK_MOCK_RELEASE(0,0,300) ZMK_MOCK_RELEASE(0,1,300)>;
		// events = <ZMK_MOCK_PRESS(0,0,800) ZMK_MOCK_RELEASE(0,0,800) ZMK_MOCK_PRESS(0,1,800) ZMK_MOCK_RELEASE(0,1,800)>;
	};

	right_hand: kscan_2 {
		compatible = "zmk,kscan-mock";
		label = "KSCAN_RIGHT";

		rows = <2>;
		columns = <2>;
		events = <ZMK_MOCK_PRESS(1,1,800) ZMK_MOCK_RELEASE(1,1,100) ZMK_MOCK_PRESS(0,1,800) ZMK_MOCK_RELEASE(0,1,100)>;
	};

	keymap0: keymap {
		compatible = "zmk,keymap";
		label ="Default keymap";
		layers = <&default &lower &raise>;
	};

	layers {
		compatible = "zmk,layers";

		default: layer_0 {
			label = "DEFAULT";
			keys =
			<
				KC_A MT(MOD_LSFT, KC_B) KC_C KC_D
				KC_E KC_F KC_G KC_H
			>;
		};

		lower: layer_1 {
			label = "LOWER";
			keys = <
				KC_A KC_B KC_C KC_D
				KC_E KC_F KC_G KC_H
			>;
		};

		raise: layer_2 {
			label = "RAISE";
			keys = <
				KC_E KC_F KC_G KC_H 
				KC_A KC_B KC_C KC_D
			>;
		};
	};
};