I've seen them in 3 places: WDW near the bus stops, at MCO airport, and in the parking garage bridge of a teaching hospital. Basically, any normal salty-snack vending machine (the kind that moves product forward with a rotating metal coil mechanism) can be used to vend PPE, but for the most part it isn't being done here.
I suspect that a big reason is that most of those machines are set up to be used with cash, which not many people are carrying much of now, and we are also in the midst of a coin shortage. (Vending machines in general are not doing that well for that reason. There are some that take credit cards, of course, but by no means all of them can do that. The ones that are most likely to take CC are bottle-goods machines, which are not suitable for this purpose.)
There is also a fairly high likelihood that people are afraid to touch vending machines, because "my gosh, when was the last time THAT was cleaned?" Even the airport car rental companies removed their kiosks, which makes zero sense to me. (You can easily put a dispenser of alcohol wipes next to the machine with signage to wipe down the screen b4 using it; which would be much safer than dealing in person with an agent.)
PS: A post above mentioned the Disney Springs WoD store selling masks. They actually don't sell them there. If you want to buy a Disney cloth mask at the Springs, you have to go to the Co-op store. They are a bit easier to get in the parks, where the larger stores tend to have them behind the registers, but they seem to be aiming those sales at children, because larges are not stocked too often, and XL is not stocked in the stores at all (at least, that is what I was told by the manager at MK's Emporium.)