kmk_firmware/docs/modholdandtap.md

ModHoldAndTap

This module allows to immitate the behaviour of ATL+TAB or CMD+TAB, etc.
Basically, it will hold the mod and tap a key. The mod will be released when any other key is pressed or the layer key is released.

Enabling the module

from kmk.module.modholdandtap import ModHoldAndTap
modholdandtap = ModHoldAndTap()
keyboard.modules.append(modholdandtap)
keyboard.keymap = [
    [
        KC.MHAT(kc=KC.TAB, mod=KC.LALT),
        KC.MHAT(KC.TAB, KC.LSFT(KC.LALT)),
    ],
]

Keycodes

Key	Description
KC.MHAT(KC.key, KC.mod)	holds the mod and taps the key