Mayonnaise serves as a binder in many dishes, so I think you can use your homemade version in just about any recipe that calls for canned soup. While I don't use mayo in my Chicken Divan, I've seen versions of the popular 70s-80s dish that use mayonnaise as an ingredient in the cheesy sauce. I would love to taste your homemade mayonnaise!
It's pretty good on a first effort, it's respectable, I think. But I mean, there's
plenty of room for improvement, seriously. I added the oil in too quickly all at once. Then, it was like impossible to get emulsification. Well, okay, pressed on. Finally just cut my losses and added the xanthan gum, that stuff really works well. Again, though, it's also my first time using xanthan gum, too, and I put too much in. I finally plastered over all the errors, but now I've got a boatload of the stuff, LOL. But at least it tastes pretty good, so I can use it. BUT gotta get frozen soon, and I know there's easily enough for two casseroles there. Much thanks on this note for chicken divan, it's years since I had that but I really liked it when I did have it. That would be a good use for it for sure.
In my opinion nearly all recipes can be improved by adding mayo

Mayo is one of my favorite ingredients.
I usually start with a recipe then add or modify ingredients to fit what I have on hand or to improve the recipe.
The first time I make a recipe I usually follow the recipe, but after that I change it up if I think it would improve with modifications.
I'm gonna try that beef one with the mayo. I know this sounds odd, I almost have gone vegan at certain points, or at least vegetarian (vegetarian I could probably still do; well, maybe pescatarian). But I've come to love beef when I can get it & LOVE pastrami and corned beef. Vegan chefs do really cool and creative stuff, but I mean I put so much effort into learning to cook all these proteins, I don't really just want to abandon that at this point. Plus, I mean, no corned beef?? Not happening. To be honest, though, we don't eat "a lot" of meat, really. But the meat we do eat, we enjoy it too much to get rid of it entirely. We could probably do the Lightlife hot dogs (they're not at all bad), but I mean no cheese either. No eggs. No milk. No way, lol, but I have a lot of respect for people who do it. (Except for Bryan Kohberger.)