Right, that's different from the previous one you linked to.
It's not clear if it does anything more than 4k60p over HDMI.
However, as it has HDMI ARC, you simply connect that port to the HDMI ARC port on the TV and connect your 4k60p devices to the TV, problem solved, as the audio will then use the ARC channel from the TV to the soundbar.
Edit: It might be HDMI 2.0, based on a review comment on Amazon, but I'm not sure. Sony really sucks at publishing real specs.
Edit 2: Ah, here we go, it seems like it's 1.4b as it can only do: YCbCr 4:2:0/Supports 8-bit only at 4k, which is good enough for TV use, but not computer use at 4k, since text will be blurry. Should be fine for PC gaming though. That said, using the HDMI ARC makes more sense and then using the inputs on the TV, as they won't limit you like this.
Edit 3: Turns out it wasn't that simple either. Sony really are playing some serious games here. Only two ports can do 4k60p and one of those is the ARC port...
HDMI IN 2/3 only. To support 18 Gbps, set [HDMI signal format] to [Enhanced format].
I think you missed his point about him having all his devices connected to the soundbar and that then connected to the TV. He linked to the wrong soundbar initially, hence the confusion. I know how ARC works.