Chimney breast being built

A log burner is a ghastly pollution producing device. 

Is the TV being flush mount?

Why not have a cavity made behind the TV in the wall, with all cabling behind?

First thought would be that placing electronic equipment over a log burner is unlikely to be a happy combination from the point of view of heat generated by the log burner.

Second consideration would be that if you use the hub for wifi, burying it away in an enclosed space is likely to have some sort of negative effect on the wireless signal.

Do some research into what kind of thing you want to create. A 'media wall' doesn't quite seem to be what you are describing but you might get some ideas below and elsewhere.

Here is a popular YT DIY channel building a media wall. It might give you some ideas of what to consider

https://www.youtube.com/watch?v=XQtv91o8Uv0

You'll need power for the TV and other devices as well as the audio visual cabling for picture, sound and ethernet if you want wired network connections

An important consideration will be cable management. You need to include some kind of conduit or duct so that cables can be added and removed as required in future without a total teardown of your media wall to get to the wires.

You'll need an electrician for the power work and, no doubt, s/he will have experience of fitting out such an arrangement.

I can't help thinking that a chimney breast will be good at blocking signals from your remote and hub. Consider instead an electric log burner installed in a fake or decorative fireplace.

Your picture shows your VM hub on its side. This is exceedingly bad for the WiFi signal, the hub should always be vertical unless you run it in modem mode.

Mounting a TV on a chimney breast over a fire sounds a very bad idea, quite apart from the VM hub. You do know that electronic devices don't like heat?