It’s most of the R6 Mark II in a RP body, with pretty much all the same settings and customisation available.
The R8 allows ISO on the top dial, two back button focus, etc.
Actually, the R8 has a few extra customisation options, when compared to the original R6, and I’m tempted to keep it specifically for the customisation. I use two back button focus, I like ISO on the top dial (where the RP adjusts aperture and doesn’t allow ISO). The R8 could give me an almost seamless experience. It doesn’t have rear dial but, honestly, it’s not that often that I need to adjust aperture.
It’s funny that you mention the joystick, because i only use it on my R6 to reset the focus point to the center. I drag it with the rear screen and reset with the joystick.
On the RP, I drag the focus point with the rear screen and reset with delete button.
Yeah, I know it's R6 II in RP body, but still, too expensive, I can buy from 1.5 to 2 used R6's for the price of a used R8, so it doesn't cut for me.
Being unable to set ISO on top dial on RP yes, that's annoying because it would at least match the R6 scheme, and aperture would go, old-style, on the control ring on the lens/adapter; instead on RP I have the ISO on the control ring, to retain at least a three-dials setup for the exposure triangle, even if different from the R6 setup.
First thing I do out of the box is disabling touch screen entirely from any camera, I don't like finger prints on the display, and I like my cameras to be controllable exclusively with mech dials and buttons by muscle memory, touch interface doesn't cut it in fast environments like weddings.
I know you don't detach camera from the eye to drag on the screen to move the AF point, but there's the joystick to cover for that (or the 4 way controller on the RP/R8), and any other touch operation would mean removing camera from the eye, and that's not acceptable for me, so touch goes off as soon as I unbox the camera because is utterly useless for the way I shoot, and if left active can only lead to unwanted operations.
I re-enable it only for video (that I rarely shoot, btw), because I'm not looking thru EVF, and so using the touch screen to pull the focus brings less shaking then using the joystick, especially with a stationary camera on a tripod head.