Asklemmy

There are many standard, or semistandard sizes of cylindrical lithium-ion cells, and devices could be designed for field-replaceable versions, but the only product category where it’s common is high-performance flashlights.

An important thing to keep in mind is that most cylindrical lithium batteries don't have protection circuitry since they expect the device itself to have it, so if the battery shorts out while outside the device, that's a really big problem. Same with many RC/drone batteries. I guess manufacturers could embed the protection circuit in one of the terminals but that's expensive so surprise surprise no one does it.

Rectangular batteries used in older phones and laptops do have built in protection, but there's also no real standard sizes and shapes. The closest thing might be the Fairphone or Framework Laptop batteries, at least those companies probably wouldn't care if someone else started making third party batteries of the same form factor until it becomes a de facto standard. Kind of like how everyone cloned IBM's PC until it became the standard.