When we started on the wall mounts, the hard question wasn't how to hold a HomePod. It was where to put one.
Apple has an answer, and it's more specific than we expected. The HomePod user guide asks for three things: keep the speaker within 10 inches of a wall, get it as close to the centre of the TV as you can, and if you're running a pair, put one on each side about 4 feet apart.
Those are numbers, not a picture. Here's the HomePod placement we landed on.
Both mounts go on the horizontal centreline of the screen — level with the middle of the TV, not above it and not below. Then as close to 4 feet apart as the screen allows, with 6 to 10 inches of clear wall between each mount and the edge of the TV. A speaker crowding the bezel looks like an accident.
Those two rules fight a little. Four feet is 48 inches; leave 8 inches clear on each side and the TV between them is 32 inches wide. Most sets are bigger than that, so most rooms end up a bit wider than Apple's number. We'd rather clear the bezel than hit the figure. Give or take.
Running the HomePod cable into the wall
This is where the centreline earns its keep. The cord goes into the wall behind the mount's flange, travels inside the cavity, and comes back out behind the TV — where there's already an outlet, because the TV is plugged into it. Nothing crosses the face of the wall. No console underneath to hide a brick and a coil of cable.
If you'd rather not cut a hole, the cord runs down the face of the wall instead. Both are tidy. One needs a hole.

One HomePod instead of two
A single speaker works, and it turns the geometry 90 degrees: put it on the vertical centreline, directly above or below the screen. Our NoBox Dad has run a HomePod mini that way for a while and it holds up better than it has any right to. Our mounts are cut for the full-size HomePod, 1st or 2nd generation, so a mini needs something else — but the placement is the same idea. Middle of the TV, close to the wall.
The mounts are here, in black or white, single or as a pair.
Let's play.