Floating Wall Brackets
This is the minimum a sink needs: two brackets, a top, and a wall strong enough to carry them. Nothing touches the floor, nothing hides the plumbing, and in a small bathroom the effect is the closest you can get to having no vanity at all while still having a counter.
The brackets belong to the Boston range and come in brushed nickel, matte black and radiant gold, in widths of roughly 15 to 20 inches, sized to carry the console tops from the same series.
The wall does all the work
Because there are no legs, everything the counter carries goes into the wall. That needs blocking between the studs at bracket height, fitted before the plasterboard, or fixings driven directly into studs. In masonry, use anchors rated well above the loaded weight of the top, the basin and the water in it. If the wall cannot be opened, a metal base with legs gives a similar look and puts the load on the floor instead.
Plumbing on show
With nothing under the counter, the trap and supply lines are part of the room. Use a metal p trap and stops in the same finish as the brackets, run them square to the wall, and if the waste can go into the wall rather than down through the floor, do that. This is the detail that separates a considered washstand from an unfinished one.
Pieces that fit
The Boston console bases and the same series tops are the natural partners. For a floating cabinet with storage instead of an open bracket, see floating vanities.