After adding six buttons to the already existing four on the Pimoroni Display HAT Mini, I was left with just enough GPIO pins for an IR transceiver (LED and receiver driven by LIRC), the antenna pin for RPiTX, and one pin for PWM audio. I needed to connect to these pins while the display HAT was attached to the Pi, and while still maintaining some measure of modularity and serviceability. 

Enter the UUGear 2x20 low-profile female GPIO header. It's only about 2mm in height which allows it to fit perfectly under the HAT header, with about half of a mm clearance for wires to pass over it. This allowed me to create a removable connector with wires soldered to a 20mmx80mm prototyping perfboard mounted to the Pi with a custom designed 3D printed bracket. The components for the IR blaster, antenna connector, and speaker will be mounted to the perfboard. The plan is to use the Adafruit STEMMA speaker for audio output.