Canon/Nikon and Sony sure have different ergonomic visions. But I think, at the end of the day, it's more about professional support, parts and service availability, turnaround and general reliability than size/ergo.
Personally, I'm in the Sony camp - I use my 200-600 for hours for wildlife with my "bare" A9 or RIV without any issues. I feel like it's really the lens I'm holding and the camera is just an attachment I look through.
Imo, Sony's customizable enough that _anything_ is just a button away without ever taking my eyes off the EVF, no need for a larger body to fit the buttons and dials. But to each their own, and it's a great that we now have all the options.
And wildlife is a bit of specialty field, AF performance ultimately trumps ergonomics for most serious photographers, I think.