I only used a borrowed NX1 for a few weeks and that was a long time ago, so I can't recall a lot of real specific details about the colors.
My recommendation based on what you want:
Fujifilm X-S10 or used X-H1: all the great colors and profiles, internal Eterna and f-log (but 8-bit internally on both, 10-bit externally on the X-H1), and IBIS. The deeper grip of both is much more similar to the NX1 and the top panel display is on the X-H1. The X-S10 also has the flip out screen, which may be preferred by you, the X-H1 has the 3 way tilt like the X-T4.
X-S10 pros: newest sensor and autofocus, likely a little better IBIS, better battery life, PASM dial like NX1 which I prefer myself especially because you can do custom modes (C1, C2, C3) just like the NX1 has. I also think it's better if you do a lot of video work.
X-S10 cons: single UHS-I card slot, no vertical grip, no 400mbps output, maybe worse EVF but I don't remember.
X-H1 pros: cheaper (used, no longer available new), vertical grip compatibility, 10-bit out, top panel LCD.
Nikon Z6/Z6II: (Z6II is worth the extra $500 if you buy new - better AF, dual slots, vertical grip)e
-- Pros: Higher dynamic range, better RAW colors, full frame, amazing lenses that are leagues above Fuji's, superior autofocus to Fuji (some people may argue about this but I returned my Fuji X-T4 after finding its AF (in both S-AF and Continuous) to be extremely underwhelming. Nikon is fast, quiet, and locks on accurately every time. C-AF is great too, even in video mode (better than Fuji, not as good as newest Sonys or Canons). Best ergonomics of any mirrorless cameras, except for maybe the Panasonic S1 which has a beefier grip and more external controls, but at the expense of significantly more bulk and weight. Also, ability to use Sony FE lenses with autofocus using the two adapters on the market. No other system can do this. 12-bit ProRes RAW and BRAW output.
-- Cons: more expensive, bigger and pricier lenses (price you pay for full-frame), no internal LOG profile but Andrew does sell his own faux-LOG profile for the Z6/Z7 here and it's quite good. 4K video is limited to 30fps vs. 60fps on Fuji. MUCH better IBIS. The best of any APS-C or FF mirrorless system along with Panasonic L and the much more expensive Canon RF cameras. Worse JPEG profiles compared to Fuji.