Where can I find a low-sodium mac and cheese recipe or product?
Unfortunately, most cheeses are high in sodium, even the low-sodium ones. I am not sure what kind of kitchen equipment that you have to work in, but you could try Foothill Farms powdered cheese sauce products. Many of their products are lower in fat and sodium.
If you can cook from scratch, a great way to stretch your cheese sauce is to start with a base of cooked, pureed cauliflower. Add some low-sodium cheese, white pepper or hot sauce and you can use that for the cheese sauce base.
Also, pair your macaroni and cheese that day with vegetables made without any added salt or broth/base as well as fresh fruit. If everything surrounding the mac and cheese is lower in sodium, then the meal in its entirety might work out just fine.
Your other choice is to make the mac and cheese a side dish (so a smaller portion) and not the main entree.
I hope these suggestions were helpful.