So, I think you may run into some significant audio issues.
Audio is always taken down to the lowest common denominator because of EDID. That is, if the TV doesn't allow for Atmos, then you won't get Atmos.
Likewise, you mention a Pioneer VSX-80, but no idea on how you plan to connect that to things, you didn't mention it.
Keep in mind that 4K and 4K/HDR are NOT the same thing. 18Gb/s HDMI is the full HDMI 2.0 specification and very few HDMI extenders support that. Some advertised units are very clear that they DO support 18Gb/s HDMI, so that's what you want to buy.
So, I'm not sure what your setup will actually be and what you are trying to accomplish. At a very basic level, secondary zones have a major issue because zone 2 often requires you to make an analog connection between the source and the receiver and this is often NOT clearly laid out in the specifications for the product. When zone 2 does allow HDMI, it often requires the source to be downconverted to stereo and requires the main zone to play the same thing as the secondary zone.
All that said, you didn't indicate that the receiver would be connected to anything.
I'm not sure what the Yamaha under the TV is for if you are using a surround sound receiver, you should use a proper center channel, or drop the Yamaha altogether and ghost the center.
There's a lot going on here, and even without discussing the headaches of 18Gb/s HDMI 4K, you have a lot which isn't completely clear.