The simple answer is yes.
However, the Nelevator was never designed to be wall mounted as such, but rather to sit in a slot cut out of the railway’s base board on its two side flanges so the entry/exit levels would be at the same level as the rest of the layout’s track. In this scenario half of the Nelevator is above the railway’s baseboard and half below it.
To mount close to (or on) a wall a special bracket arrangement would have to be constructed. The mounting flanges on the side of the Nelevator are 30 mm wide on each side. So realistically the Nelevator should be able to be mounted within 30 mm of a wall.
The only real problem with mounting the Nelevator so close to a wall would be gaining access to take the rear cover off should any major derailments occur, but access would still be available from the front and underneath.
If it’s acceptable that maintenance issues could be a little more awkward if they arise, then there shouldn’t be a significant reason to prevent the Nelevator from being mounted in such a way.