I already had a nikon Z6 with the 24-70 f/4 kit lens before I boight the GR III and I still have it, although now with the 40mm f/2. I reach for it when I am not using the GRIII and when I think I can afford tje kuxury of carryknf out the extra weight. I have to admit, I still love the images from the Z6 a lot
That said, since I bought the GRIII in Jan this year, I shot over 3k images with it and perhaps less than 50 with the z6. Says a lot about how much size and portability can matter more than image quality for a hobbyist street photographer like me.
I also brought a second hand Nikon J5 (1 inch sensor) in Feb this year and have had quite some fun with it! Funny enough, even though the J5 camera body is smaller than the GRIII, it is thicker and therefore less pocketable.