Observations from the two Osprey images,

Top image : D7200, 400mm, f/6.3, 1/500, ISO200
Bottom image : D7000, 400mm, f/8, 1/1250, ISO800

These images are very severe crops, a 400mm lens on an APS sensor with a subject distance of 200yds gives a horizontal FoV of approx 12yds.

Both cameras have the same sensor size but you have presented two images both taken at 400mm with two different crops. The D7200 image posted is a far greater crop of the full framing, which is an unfair comparison.

For a truer comparison, both nest 'cages' should have taken the same width within the frame. In addition different, speeds, apertures and ISOs does not equate to good equivalency practice.

I'm confused. Why are you doing this bit of photographic masturbation. Take the camera, and you lenses out and shoot photos. Take them home and print them out to a decent size, depending on your printer 13x19, 17x22, etc. Evaluate the prints. Do you like what you see? Then go out and take more photos as long as it remains operational. If you don't like what you get, get rid or return the 7200 and rent other cameras and shoot photos with them. Pick the one you like best. Wad up and throw away the test patterns. They bear no relationship to real photography.

I own a D5600 and must disagree. This poster is clueless.

The D7xxs, prior to the the D7500, have a sucky control system: randomly placed unlighted buttons, an unreadable little green screen, and an inactive info screen. The D5xxxs have always been controlled through an active info screen. The D5600 takes it to a new level with the touch screen.’

And the D5xxxs are half the weight and price, and have an awesome fully articulated screen.

And they have the same sensors and take the same images as the D7xxxs.

Zone 0 is no detail shadow, zone 10 is no detail white, zone 5 is halfway between &etc. Working within that concept of course digital can work from O to 10. The zone system is not about matching but adapting your equipment so you can get predictable results.
I use(d) my spot meter to read the area of a scene that is important to me and then, based on how I want it recorded, make my exposure settings. The process is about getting the exposure where you want it and for that purpose the range of my meter is not at all relevant. I also don't expect to get a full range of values but to expose the scene so the values I deem important are recorded where I want them to be. That is what the zone system is all about.