I’ve got three of the AG Ones, and no wall mounts 
The One has four ‘keyhole’ slots on the back - left, right, top, bottom.
Fit screws in the wall to align with the keyholes as required, the just hook the One over the screws.
You could just use one screw, with no alignment, and hang the One via the top keyhole…
If you want a more secure fixing, where the One won’t move, then line up two screws for the middle (left and right) keyholes.
The hardest part is getting the screws in the right position so that they are dead centre with the keyholes, and level. Sometimes devices that are mounted come with a paper or card template showing exactly where to put the screws, which makes alignment dead simple, but I don’t think the One had a template .
See this: