The A7C should meet both your requirements:
1) You can setup the rear dial or wheel as exposure comp, if you prefer that over the dedicated dial. They will definitely be easy to rotate. The thumb dial better for that than the wheel, when at eye level.
2) There are zebras as well, but I haven't used them. The new Sonys like the A7C, also have highlight weighted metering that prevents them from being blown out, when using the camera's internal meter.
As for FF vs m43, you will definitely get better separation due to the longer actual focal lengths.
Is size a priority? If not, you have a ton of options that m43 would not be able to compete with. Even if you are concerned with size, you could get the Sony 35mm 2.8 lens. That combo with the A7C, is not much larger than the Pen-F and 17mm 1.8, while offering much better low light performance and improved separation of subject from the background. I've had both combos before and the Sony is much better in terms of IQ, but that Pen-F / 17mm is more "fun" and has more "soul".
You're right about the RX1Rii - battery life stinks. Very very poor. The A7C will go on for days with it's Z battery. But, the other two gripes - no IBIS and poor grip - can be overcome with faster shutter speeds (high ISO is great on that camera) and an external add-on grip like the Fotodiox one. Again, I've also had the RX1Rii and still miss the IQ from the 35mm f2 Zeiss lens and the overall compact package - nothing can compare to it in IQ per pound imo.
Going back to the A7C, if you are ok with a lens the size of the Samyang 35mm 1.8 you referenced, you may want to consider the Sigma 35mm f2 I-series lens. It appears to be the closet to the RX1Rii Zeiss lens in terms of rendering.
Size comparison:
Compact Camera Meter