I have a Fighter in my game trying to use a Magic Missile Wand as a One-Handed Weapon Attack to get the benefit of the Crossbow Expert Feat. The Crossbow Expert Feat requires that the player make an Attack action with a 1-Handed Weapon. I ruled that the Wand of Magic Missiles (from the DMG) is neither a weapon nor using an "Attack" action.
My reasoning is that the wand is specifically classified outside of the "Weapons" section of the Magic Items guide, and I believe activating it is similar to other magic items that have spell effects. Activation of a magic item does not make for an Attack action as defined in the PHB, if anything it would fall under the "Cast a Spell", or "Use an Object" action.
If my ruling is correct, looking ahead, the Extra Attack class feature of a fighter will not allow him to use the wand (or similar item) as an Extra Attack.