I have some items that I try to stock up on when they're on sale. So sometimes an item will have IOS written after it, which means, "If On Sale." That means we're not out, but it's worth looking at the price and maybe stocking up. There are a couple things I can think of that are occasionally, "buy 1, get 2nd for 40% off."
I saw you mention that "IOS" idea somewhere else and now I use it myself on my lists.

If your local food stores are anything like ours, then you probably are looking at lots of empty spaces where there should be product. It's getting a little better, but lots of items on my list are just not in stock when I shop. So, I propose another reminder, like IIS2 "If in store, buy 2". Easily changed to IIS3, IIS4, etc...
Dear Wife has never had to manage our food and household supplies before the COVID-19 lockdown period when lots of things went out of stock, and stayed out of stock, for long periods. I have been patiently training her on how to build up a storage pantry, buy extra if on sale, or buy 2X or 3X of "never out" items for us that always seem to be out of stock and hard to find.
I grew up in an older house with a very nice built in pantry room. My parents were great on stocking and rotating our goods. Dear Wife has always lived in the "only buy it when you need it world." But the world has changed and now we often cannot find supplies in the stores that used to always be on the shelves. A well-managed pantry and buying items when on sale can save lots of money and cover you in those shortage periods.
I am a big fan of using lists. "A short note is better than a long memory." Since I only go into town and run errands once a week, I add items to my list as I think of them. When I run my errands in town, I cross off the items I purchased but leave the other items on the list that were out of stock. Then I use that same paper list to continue my next week's items. That way I don't have to rewrite those items that were not in stock over and over again. Eventually, you have to start a new list, but at least you still have a record of what you need to buy if they are in stock on the next run. If I don't keep track of those out-of-stock items, I almost always forget about them on my next errand run and kick myself when I get home because I forgot to look for them.