Not my exact area of expertise but we went through something similar here in Asia where sellers rushed to clear stock before the government stepped in with price and export controls.

If you have the logistics set up already then you could quickly sell them on:
* Facebook marketplace.
* eBay.
* Amazon yes, but run the risk of them closing down your account.
* Local classifieds and Craigslist.
* Reddit though just be wary of each subreddit's advertising policies.

As for how to package them, the most popular configurations I have seen here are 5-packs or 10-packs as they need to be changed on a regular basis.

Assuming you had time and skills to get a basic Shopify store setup in a couple days, I would suggest building your own store. That way you would own the traffic and transactions that are coming in through there.

The traffic will be just as effective to come FROM those same areas that have been suggested, but the transactions occur in an area that you control.

The packaging question is dependent on how you ship them. If you have the basic infrastructure, you could package them individually and make more profit. But if you don't, and mostly want to offload them easily, then I would suggest keeping them how they're currently packaged and send them out.

Hope that helps!

A friend of mine in Montreal built a team of "phone salesman" and is now selling thousand of disposable face masks every weeks, mostly to B2B.

Last I heard they are selling for $75,000/weeks to big store in Montreal (Walmart, Costco, Supermarket, etc).

I would suggest reaching out to big store chain in your area to see if they would need them and sell them in bulk.

Good luck!