I've been shooting my Z9 every day for over 3 weeks - wildlife mostly but 'general' photos too. Just a superb instrument with the 24-120 f4S, and adapted F-Nikkors, including 70-200 f2.8E, 180-400 f4E TC, 500 PF, 400 f2.8E). Its AF brings new life to Teleconverters, especially the 500 PF+TC14 III.
Nonetheless, I have also listed closing on 30 fixes to firmware, which can only improve what is already an excellent camera. Most of these overlap with Thom's Firmware list in his Z9 Africa Blog, and Brad Hill's List, which is collaborative: pooling contributions from several wildlife photographers.
Expansion of fps and the AF (10+ AF options) - let alone 8K video - are overwhelming for the external controls the Z9 has inherited from Pro DSLRs. Exposure is seriously wanting in Custom options: to enable speedy changes especially.. Thus IME, besides awaited firmware fixes, the Z9 is missing physical Controls - AE-L would help immensely by assign 1 more AF Area mode+AF-On Custom setting for a toggling Hybrid-Button-Shooting (Next to AF-On used for BBAF). Besides Nikon removing any option to toggle Exposure modes (Spot-mode especially) a dedicated Exposure button will be a great help.