Calculators are large enough that it should be possible to fit AAA or AA sized batteries, even possibly a 18650. They're lower power enough that a CR3202 lasts a long enough time but it always ends up dying at the most inconvenient time and they're really the only device I have that needs CR3202.

You'd need two AAs or AAAs for a CR2032's voltage. While it would last a lot longer, it's also a lot more volume. Also, the diameter is going to be a problem for many calculators; e.g., the R47 being discussed here is 12mm thick, a AA has a 14.5mm diameter and a AA has a 10.5mm diameter.

Huh, interesting points. I wouldn’t have thought of that because I ended up with a passel of widgets using those cells, including car key fobs, Apple AirTags, and a number of IoT sensors around the house. I own exactly a single flashlight that uses an 18650. Go figure!