Promaster announced a new extension tube set for Nikon Z-mount. The set includes 11mm and 16mm tubes:
“Extension tubes are a perfect solution to allow ultra close focusing without sacrificing the optical properties of your lens. ProMaster Macro Automatic Extension Tubes are engineered for a precise fit and proper communications between your camera lens and body. The ProMaster 6520 Automatic Extension Tube Set for Nikon Z mount includes two tubes that can be used individually or in combination to gain the right magnification for your particular need.”
A few other Z-mount extension tubes options from different manufacturers already exist online at Adorama, B&H and Amazon.