Note that running power thru a wall has to be done properly. You just don’t punch a couple holes and drop a cord thru it. That violates code … and it’s in the code because it’s a safety hazard.
HDMI cables and such are okay this way, which is what the simple access covers as given above are legal to sell.
There are systems that take care of the power feed properly. Make sure they include a channel cover. The ones without them, some sold by big name companies , are a no-no.
Even better is a proper Romex run. In any case, remember to enclose the openings in an electrical box.
I mounted my TV last year and love the effect. In my situation, below the TV I have a short gap of white drywall and then a dark brown wainscoting. For the first part, I got a simple white tube, sliced one side, and put the wires thru that for the top part. The black wires are barely visible against the wainscoting.
If you have another color, paint the tube.