Theoretically, I think it can work but I don't really get a chance to try by myself. Anyone else has experience?

I don't believe an HDMI extender would work over powerline as it's not IP traffic AFAIK.


On the subject of Sky - this might help someone:

I use Sky Q within my house via the built in WiFi mesh to a couple of Sky Q mini boxes and a Sky Q booster. All standard there.

But it also works over powerline connected to the Ethernet on the sky box to an outbuilding a good distance away - where I have a Sky Q booster connected to Ethernet and another couple of Sky Q miniboxes connected to the booster via WiFi....

So you can run Sky Q in multiple buildings from one dish provided it's on the same LAN. And subject to the limit of 3 mini boxes turned on at once I think?