Photoshop CC (2017) Showing desaturated/less contrasty images compared to LR

Can you post a side-by side screenshot?

What calibrator are you using?

BTW there's no particular reason color settings should match, you can set them to whatever you like independently. Photoshop will preserve any incoming profile.

Ah, this isn't about color profiles. It's about different on-screen resampling algorithms with extremely noisy (or binary) images. Yes, stars are equivalent to noise in this context.

You need to view both at 100%, or 1:1, which maps exactly one image pixel to exactly one screen pixel. This is the only really truthful representation of the file. Then they will be identical.

On-screen scaling softens the image, and the effect varies with different algorithms.

There's no workaround as such. When you display, say, a 6500 pixel image using 2500 pixels on screen, something has to go. The question is what. How do you treat a 2-pixel sharp transition when you have less then a pixel to do it?

In a normal photograph this isn't a noticeable problem. But when you have lots of very sharp pixel transitions - noise or stars - there are different ways to do it.

If 100% is too close, try the regular intervals like 50 or 25, rather than fit or fill.