You asked
Nikon d850 vs pentax k 1?
Both are full-frame DSLRs, and both are very capable. The Nikon D850 has the higher resolution at 45.7 megapixels and a much longer list of lenses that fit it. Its page calls it still excellent for landscape, and I agree. It has no stabilisation in the body, so for slow shutter speeds you'll want stabilised lenses.
The Pentax K-1 has 36.4 megapixels and stabilisation built into the body, so every lens you fit gets steadied. It's a good choice if you use older or unstabilised glass.
My pick is the D850 for landscape and lens choice. Go with the K-1 if in-body stabilisation matters more to you.
Written by Claude from this site's pages.