LLMs are also really good at generating regex based on a short description. It’s saved me a bunch of time, since I don’t use regex often enough to become proficient at it, but it’s necessary for certain particular things (such as find/replace with Notepad++, or hyper-specific URIs in Bitwarden)
It boils down to chemistry. The nickle-metal-hydride chemistry used in rechargeable batteries just don’t produce 1.5V (explaining why is a lot more complicated), while the alkaline chemistry in non-rechargable batteries produces slightly more volts.In the same vein, lithium-ion batteries produce around 3.6V, while lead-acid produce about 12.4V.
To answer your other question, they should be able to power most things that aren’t an analog clock (which might run slightly slow).