If you are looking for QMK inspiration, here’s my keymap.c code. It is for a KBD75 but QMK works with a wide host of keyboards.

I’ve included the following features:

Enter and Tab keys are “mod taps” for HYPER, meaning when tapped they each perform their normal function, respectively, but perform Control Option Command Shift when held.

CAPS is a “layer tap” where it serves as CAPSLOCK when tapped but brings up Layer 2 when held.

Shift keys use “Space Cadet” where tapping left and right Shift individually yields open and close parentheses, respectively; but regular SHIFT functionality when held.

The Layer 2 Escape key sends Control + Command + Q to lock the Mac display.

There are three text macros used in conjunction with Sys Prefs > Keyboard > Text within macOS.

I added RGB commands to led_set_user to program the RGB underglow to a specific color until CAPS is engaged, which turns the underglow red when tapped; tapping CAPS off returns the underglow to the originally programmed color.

What macros and features have you used in your keymap?