Devices that are essential to life have build in battery indicators and plenty of those will give an error when it noticed the voltage curve is incorrect (or they detect the differences and block it as it's not
intrinsically-safe in that configuration; ATEX/hazloc rated items). These range from avalanche beacons to industrial measuring devices. For smoke detectors; those tend to be more basic, but those will not provide battery alerts either when the voltage doesn't drop.

They will probably work with most regular items. But i personally don't have things that require more power density in AA/AAA form.

I appreciate the responses and information.

It seems the consensus answer to my question is "no." That's useful.

I'm going to start poking around for simple 18650 headlamps. I've been playing with the raw/unprotected ones for years, charging them directly off a 15W solar panel (monitored closely) and running old LED lights directly. They do seem to be better in many ways. We'll see if the protected ones are as good -- I have a charger on the way.

But all this belongs in another thread.