I live in a Chicago suburb, and while variety did decrease (I still can't get Coke Zero Cherry) the basics were always in stock throughout the pandemic time.
Why? Because the channel mix changed, and distribution and packaging are channel-specific.
For example, toilet paper is shipped to commercial customers in cardboard boxes, while retail customers by it in plastic-wrapped, branded, and SKU’d blocks of 4, 8, 12, etc. When everyone suddenly stopped going to offices and restaurants, demand plummeted in the commercial channel and soared in the retail channel. It took time for factories and distributors to adjust to that. The same thing happened to a bunch of food staples too.
Since a lot of manufacturing is regional, different areas of the nation and world experienced different impacts.
Part of the problem was state government response. After each further restriction, people panic bought more.
The issue wasn't a shortage, but a shortage of flour in small bags.
Interestingly I saw some supermarkets fill up bags they usually use for bakery items to just sell the flour which seemed like a smart solution!
Also in March/April last year hand soap and toilet roll was hard to come by.
But as mentioned, my GF pasta was fine.
And I don't think anyone really starved as most of the shelves were full of something. Just reduced options thanks to hoarding.