For context: I am an amateur photographer doing street, landscape, family, social events and nature. My iamges are displayed on the Internet, on PC , Phone, and TV screens, and printed mostly up to A3. My current gear assortment is pretty large - driven in the past by the feeling that I need something special for each and every occasion.
For a couple of weeks now, I have reduced my gear to two fixed lens cameras: The Sony RX1R M3 and the Sony a6500 with the Sigma 90f2.8 firmly attached to it (so firmly, it now qualifies as a fixed lens camera :-) ) !
The RX1R M3 is a marvelous camera regardless if price. Small, yet with a good EVF for the size and three focal lengths included: 35(FF), 50(APS-C) and 70(M4/3). That is really all I need on a daily basis. A moderate WA, normal perspective, and a short tele. Pretty much the set my father started with back in the 50ies. Wider that 35mm are for effect, really. Done that in the past but am tired of it. I have done weddings and anniversaries with the RX1 with much success!
Longer than 70mm (and I can crop the RX1R Mk3 file to 100mm in post) is needed to increase compression or for more reach. This is where the a6500/90 combination comes in. The a6500 image quality is very good, it comes with a flash and IBIS (unlike the a6700). It uses the same battery the RX1 uses, and it includes a digital crop of 1.4 and 2x with up-sampled JPEGs. That turns the 90f2.8 into a 135, 200 and 270! Very good quality output for my uses. The camera is in a small pouch when I take it with the RX1 and doesn't really bother me. Often I know that I will not need a long tele on my photo walks. But I did get some nice shots in Berlin using a 200mm lens.
Why the a6500 and not the a7cR? The latter offers HEIF, much improved AF, IBIS and more MPs. But it also has no flash, a different battery from the RX1, and is larger and heavier. The difference in image quality doesn't really show in my use cases.
Reducing my gear to these two cameras is liberating. Still like my Fuji X-E5 and the Fujicrons. But they are currently spending much time on the shelf - and so is the rest of my Sony gear.
It's great than your subjects are so close and it works for you. I prefer a 600/4 and 100-400 or 100-500, so unfortunately it is not realistic to have the lens permanently attached. Most species will either attack or run/fly away at close distances.