The Zf does not support cable release or remote triggering of SB-5000's via radio; does not support vertical grip and uses only those very small and flimsy SD and MicroSD cards. The Z6 III supports all of these accessories and proper memory cards.
If I had had thought it possible that Nikon offers zero cable release options for the Zf, I would not have purchased it. However, I got over my shock and love the Zf for its thin profile and dials. But it doesn't service as a true backup camera as if I use the SB-5000's on my primary camera and the latter fails, the Zf, nice as it is to use, cannot take those shots with remote flash. So in the end I have to purchase yet another camera.
As for Panasonic, Sony etc, they don't work with my Nikon lenses or accessories even to the degree that the Zf does. I wonder how many people spend thousands of euros on a camera body and is not already in ownership of multiple lenses and accessories and thus basically to maintain interoperability has to stay within brand. I can't really think of anyone. Sure, you can own multiple brands but how does that make things easier? Building of reflexes for instinctive use of the camera is important so having to deal with different button layouts, different directions of mounting lenses, different menus all make it harder to always be ready with the correct settings when the moment of a lifetime presents itself. So no, not considering other brands of cameras at all. Would I consider them if they used my Nikon lenses? No. Nikon already makes too many UI changes seemingly in a random fashion, switching between brands would make it still harder.
