As a user of Leica SL3 I have had GRiii as my main pocket camera.You're probably right, of course, but I was thinking size/weight are somewhat relative...And coming from a D850, either an X-t5 or an Zf seem to much smaller/lighter.
I got some good stuff with my old CyberShot for that matter. I guess I'm looking for something in that sweet spot that still seems like a "real camera" with a viewfinder...and maybe even interchangeable lenses.
Some months ago I added a X-T5 (and later a X100vi).
The X-T5+lenses feels considerable lighter than the SL3+lenses, so you will feel quite a difference compared to your big Nikon.
XT-5 is a fun camera for me with the analog dials. I first wanted small lenses, but ended with the faster primes after reaing all the stuff in the internet, in order to get better IQ and smoothe bokeh. Still lenses like the 23 or 33/1.4 are much smaller than comparable fullframe counterparts. Same if valid if you compare the 11-24 to a comparable full frame lens. I now carry a combo of x-t5, most often 11-24/33/90 in a pretty compact bag.