Aren't you making a fairly unreasonable assumption that need is also accompanied by ability to pay elevated prices?
Price gouging can easily make a scarce critical good unobtainable to poor people who need it before the price is high enough to discourage all the rich panicking hoarders/preppers.
In emergencies like this, there isn't enough supply available anywhere to meet demand. The manufacturers can't scale fast enough - and even if they could, they're often unwilling; scaling up has large up-front costs, so it's not worth doing if the demand is going to evaporate before they can recoup their costs.
The right solution here is for the governments to start issuing very large orders, thus ensuring the manufacturers can scale up without worries, while distributing the masks to everyone in an equal fashion. And jailing the price gougers for profiteering off global emergency while we're at it.
In the presence of price gouging laws perhaps, but not in general. I of course acknowledge the overhead cost of retrofitting existing manufacturing setups to produce masks, but that doesn't mean they can't still turn a profit, especially if they are not prevented from selling internationally by well intended but misguided laws.
Price gouging laws do not change the underlying facts of how long it takes to spin up new production lines. In an emergency, suppliers cannot respond quickly enough, by definition. The problem to be solved is how best to allocate existing stocks and production output, not how to incentivize new producers.
Of course they don't. What they do accomplish is preventing prices from rising quickly enough to justify new production lines. It really comes down to if manufacturers think they can make enough to cover the costs of changing production lines to the emergency good, then turning them back, and then some. This is compared to how much they make doing what they have always done. Price gouging laws lower the profits they would make.
How does this matter, if either way the new production line won't be up and running until after the emergency is either over or has been seriously exacerbated by poor allocation of goods? It seems like you're still trying to pretend that markets are efficient and can always respond quickly, and that's simply not true.