As of this post (Jan 18, 2022) no one is yet making L brackets (or even bottom brackets) to mount a Z9 on an Arca-Swiss style tripod. (Or so I think - if someone has a source please post below). Nikon is already shipping the camera but people can't use it with their tripod? Both Kirk and Really Right Stuff just have place holders showing that they plan to make them. They don't even have a picture or price yet (they both show a picture of the camera but no plate). This in spite of the fact that Thom Hogan posted exactly one month ago that both companies make them (perhaps he didn't bother to check the links he provides?). The only thing I see currently available is a SmallRig cage for video setup (horizontal mounting only). Considering the immense popularity of this camera I hope RRS jumps on the ball soon. (What is concerning is that someone posted a question on their page a month ago asking when it would be available and they haven't even bothered to answer that person's question).
One can always use a generic arca swiss plate in the meantime right? Meaning just a plain flat plate?
Here in France AMAZON have a SMALLRIG 'shop' and as far as I can tell most is shipped (initially) from Germany so no taxes etc. and the shipping is almost immediate.