QYT KT 7900 has all required signals of 3.5mm TRRS headset socket:
This connects to Digirig’s 3.5mm TRRS audio socket:
QYT tip → DR ring 2
QYT ring 1 → DR ring 1
QYT ring 2 → DR tip
QYT sleeve → DR sleeve
For extra credit Digirig’s serial port can be connected to QYT’s programming port.