the G7X seems like a very attractive option, similar size to RX100 III/IV with a longer reach and equally bright. price much more attractive too. anything difference I should look out for? I don't do video
If your not into video you can scrap the Rx100 mkIV. As the the Rx100 mk3 is nearly the same in terms of stills. Just a tad bit slower lower res EVF which isn't the best in the mk4 either. Both lack a good eye relief needed to use them comfortably for long durations.
You mentioned the key G7x advantages and i will add 2 more. It has a nice touchscreen.
The lens doesn't have as much aspherical elements and is less nervous in the OOF area's as the Rx100 mk3/4
Then as things to be aware off.
It can only shoot 0.8 fps in raw with autofocus. (g7x mk2 adresses this issue)
The lens is soft in the corners between 24-35mm. as it just doesn't cover the whole sensor and the camera has to stretch the image significantly. Which makes using this camera at the wide-end quiet problematic
Just scroll down to the uncorrected raw test scene for confirmation
It doesn't have a viewfinder. Which can be a problem under bright conditions. Judging exposure on the rear screen in direct sunlight is impossible on any camera.
With the G7x i would certainly get the mk2 version instead of the first one. It's 10x faster in raw and possibly in regards to AF too. Whether to get it instead of the Sony. That would depend on what you like to use it for. The Sony will do better architecture and landscapes. The Canon will do smoother portraits.
Your stuck with the lens. So get the one that suits your shooting the most.