However the voltage on alkaline batteries drops pretty linearly from 1.5v to 1.0v, while rechargeables maintain close to 1.2V for most of their discharge, then drops off quickly:

https://www.boat-project.com/tutorials/aa_batteries.htm

That's why rechargeables work in most devices, since alkalines are 1.2v or below for a good chunk of their useful life anyway, most devices are designed to work fine with 1.2v.

If a device actually needs 1.3+V to function properly, alkalines won't last long, you'll want to use 1.5V lithium batteries.