What I do is go through the thousands of images and average out what is the most common focal range I used.
You can buy good slightly used 24-70G versions from those up grading to E.
In my experience about $1300 AUD gets you a good 24-70 G, buy it from a good dealer.
Look the 24-70 G or E lens is simply a bullet proof reliable work horse made for serious full professional applications, ie working hard all day etc etc in commercial applications weddings etc etc, its a safe lens, sharp fast accurate versatile, its part of the wholly trio of lenses.
I find the F2.8 in any lens is simply essential, not just to shoot at 2.8 but the fact I need less iso and get better speed and focus performance.
I have the 14-24G, 24-70 G, 70-200 FL, these lenses are the go to lenses other than for long wild life sports action.
14-24 2.8 is a stunning all round paparazzi lens that is also spectacular for landscape, street photography and creative shots, fast sharp accurate a bullet proof work horse, not a consumer lens like the 16-35 f4 that for many vignettes with several filters and pushes you out to 19mm, The 16-35 is sharper in the middle by 20% but softer in the corners where the14-24 is sharper evenly across the frame. the 14-24 is the better choice and suits astro shooting better because its 2.8.
Don't do your head in, just hire before you buy and don't get caught up catching GAS disease, focus on composition.
As to the D850, its a brilliant all round do everything well camera that really requires good glass like 2.8 to get the best out it, it allows you to do everything, there is nothing much that the Z7 can do that the D850 cant, remember a camera is only a toll that records light which is a photon of red green and blue, what varies is the glass, and you behind the camera using it.
Yes if am traveling and don't want a heavy lens etc I take a 50mm 1.8, or a 24-85 I have had for ages.