Short answer: No.
Long answer: follows...
Back when Fujifilm was rolling firmware updates constantly many were impressed with their so-called Kaizen notion ("continuous improvement"). I wasn't. Fujifilm was doing in firmware updates the two things that would cause you to make a firmware update:
- Correct errors, fix bugs, correct performance.
- Add features and functions that had to be dropped from the critical path to launch.
Quite a bit of #2 found its way into early Fujifilm firmware updates, mostly because Fujifilm had a long way to go to catch up to all the features and functions the mature platforms already had. You don't reinvent Rome in a day (though you can burn it down in a day, apparently).
Fujifilm even tended to roll those features and functions to older cameras (models that weren't the current generation), mostly because it was easy due to a common code base that hadn't started fragmenting yet.
"What happened to Fujifilm Kaizen?" became a widespread question on the Internet starting in 2019, as Fujifilm got their features and functions more up to the level of their competitors.
A similar thing happened with the Sony A9, where the initial shipping version had a number of incomplete or missing features compared to the top Canon and Nikon cameras Sony was targeting. Sony, for example, found that at the Korean Winter Olympics—where they were hoping to make a big splash—that the big agencies immediately pushed back when they found that the initial A9 firmware didn't put the serial number in the EXIF data (the agencies track photographers via serial number). Lots of other little missing elements were found that also impacted the agencies, and Sony fairly quickly iterated the firmware all the way to version 6.00.
To put this into Z context, the original Z6 and Z7, as well as the Z9, all represented Nikon's first efforts at something in mirrorless. Did everything they wanted make it through the abbreviated development schedules and get into firmware version 1.00? Not even close. All three cameras had clear missing elements in both function and performance on day one. And thus, it's to be expected that we got both #1 and #2 types of firmware updates for those cameras.
Z6 II and Z7 II users are currently complaining that Nikon owes them a firmware update. I'm not so sure about that, even though there are functions I'm still complaining about not being in those models (wake up Nikon! Everyone wants two basic things: AF-ON+AF Area Mode customization, and 3D Tracking instead of Subject Tracking).
My suspicion is that the II models are pretty close to where Nikon thought they needed to be, and that their focus these days are on trying to make sure that the III models get distinguished from them. Would I like a significant firmware update for the II models? Sure. Do I expect one? Not so much.
The expectation problem, however, is real for Nikon: there's no true backup for the Z9. That's because the Z5/Z6/Z7 foundation is quite different than the Z9 foundation. User Settings versus Banks. Mode dial versus button. Subject Tracking versus 3D Tracking. The list goes on and on, but I'm not sure that it's correct to think that the Z5/Z6/Z7 models get "conformed" to the Z9 ideas. It's more likely that we're going to have a new body (or bodies) that conform to the Z9 ideas while the lower models mature out via iteration now.
I don't like the status quo any more than you do. In the DSLR world, I had the D500, D850, and D6 that all paired together well due to common controls and feature sets. A mirrorless Z9 and Z6 II or Z7 II simply don't pair nearly as well, and trying to make them do so through firmware updates would have the potential of ruining their nature for the more general user base.
Do I think Nikon will make another "significant" firmware update for the II models? I suspect so. And I'd guess that would come just prior to launch of III models (so as to give the previous generation a longer product life as discounted models). Will that fix all the things that I'm hearing Z6 II and Z7 II say they're "owed" updates for? I doubt it, as these are already highly competent cameras. However, they're highly competent consumer cameras that stretch a bit into prosumer, not highly competent pro cameras. Most of the things I'm hearing people ask for would be in the pro, not consumer realm.
It's really tough for a company to be consistently on top of the game these days. Nikon's managed to do that with the Z9 and all those great Nikkor S lenses, less so with the other camera models and non-S lenses. So I understand all the pent up emotion about owed firmware updates, I just don't think Nikon has the bandwidth to make all those people happy, and thus won't.
