Images from Nikon Z7 looking normal in preview both in mac and windows but looking over contrasting

In the image viewers, you are looking at the embedded jpeg preview (from the camera if you haven't updated the preview) - not the raw data.

In Lr and ACR you are looking at the raw data with your default settings applied. If you don't like your defaults, change them.

As for noise/grain, camera processing always has very aggressive noise reduction applied. In Lr/ACR, you have to dial it in yourself.

Raw processing in Lr/ACR is based on your own choices.

What presets do you have set in LR and CR?