The latest Nikon Z6/Z7 CFExpress firmware update supports only the new Sony CFexpress Type B TOUGH memory cards (read and write speeds of up to 1700MB/s and 1480MB/s). A quick check with online retailers shows that the Sony CFexpress Type B TOUGH memory cards are expected to start shipping next week, on December 25.
Pre-orders are now open at Adorama and B&H Photo.
A new Sony MRW-G1 CFexpress card reader is also available:
Additional information on the Sony CFexpress Type B TOUGH memory cards: