I am curious why though? Why have a camera as capable as the R5ii and only use it for wildlife and such? I notice R2D2 you also have the R5, would you say the R6ii is more fun/practical/responsive than the R5 and why, I am interested to know. I'd like a second body too but it would have to be;
Currently there isn't a lot of options in this space except, R5/R5ii from Canon and the Sony a7r5/a1ii which requires me to run a second system that really doesn't interest me. So, I do wonder why R5/5ii isn't more popular for the everyday duties, please explain?
You are massively underestimating the capabilities of a small body such as the R8. IBIS is very very often not as relevant as many seem to believe and other than that the R8 is really fun to use (especially if you don't need the second card slot and often look at the display instead of the EVF anyway). I have all three, the R5 II, R6 II and R8, and in general if you don't need any of the R5 II exclusive features like eye control, RAW pre-capture, scenario based AI AF or high resolution, the R8 and R6 II are really close in terms of AF and general operation performance.
Why use this super expensive camera for "everyday activities" if an R8 or R6 II can basically do the same with a bit less resolution (which often isn't that relevant either)?
"Wear out" your most expensive geare wisely. Wildlife is one application where the R5 II has some welcome improvements over the less expensive bodies. For some other applications like event shooting (where you need the best of the best reliability and overall performance) R5 II is the prefered choice, but the other bodies are no slouches either.
The R5 on the other hand pales a bit in comparison, as it doesn't have the latest "AF interface" like the R8 and R6 II and therefore a different way of operating the camera is necessary that can be a bit tedious, especially if you are used to the newer implementation. Nevertheless the R5 in itself is still a great camera, just not the best fit as a second body. R6 II, R8 and R5 II can be configured to behave very similarly and have a similar UI layout as well.