After they upped the amount of Meltan spawns per box to 19, someone with access to a Switch can get 114 candies per use off of Pinap catches alone, more after factoring in transfers and trades. It would take someone 4 box uses to get enough candy to evolve one.
While I don't think it would be unreasonable to ask for one via trade, why not meet up with someone with a Switch to catch them yourself? The Switch titles can receive Pokemon from any given account and distribute boxes to them as well, they aren't locked to the Switch owner. I don't own a Switch and have gotten my own Mystery Box by transferring to two different people.