You don't think Apple has literally one of the best distribution networks in the world? What percent of the country is within a few miles of an Apple store that already receives shipments a few times a week?
Apple stores aren't getting any shipments right now. Even if they were, those stores are closed and Apple isn't going to open them to sell a few face masks to consumers. By the time Apple stores open, even fewer people will want face masks. (And Apple won't want them on their shelves regardless)
Apple's distribution network is built around selling consumer electronics, not medical supplies.
This isn't remotely the sort of product Apple would manufacture and sell. It's not worth the time and effort to design retail packaging for it.
A lot less than you think. Huge swathes of the country don't have Apple stores. Even living in the Puget Sound region, my nearest Apple store is 25 miles from me.
By and large Apple distribution is "UPS". Both to wholesale and retail.
