Not really. It could work as a Slide Over kind of window, or like Quick Notes. I’m surprised they didn’t at least add it for devices that are now getting Stage Manager, it’d be perfect for that.The only way to bring a Calculator app into iPadOS is to implement proper app windows, where app windows can be small by default.
The approach it seems with the new iPadOS is just big iPad apps scaled down. That means apps need to be designed to take advantage of the entire display, which in turn will look like a waste of space and will be ridiculous looking.