The Titan Pocket has a 4000mAh battery. Small devices tend to have different use patterns since they are less suited for watching movies or playing games. I charge mine every other night but I think it can get through 3-4 days if needed.

I'm not sure battery life is going to be worse just because it has a smaller battery. At a constant DPI, the CPU/GPU doesn't have as much work to do to paint with a smaller screen, not to mention the screen itself consuming less power. Even if the battery life were worse, I'd want a smaller phone.

I'm still using a Z3C with LineageOS. At some point it will kick the bucket. I barely use it save for phone calls, and minor conveniences (e.g. vaccination proof, tickets and such). Part of me thinks I should just bite the bullet, accept a larger screen, get a PinePhone, and find a way to start contributing. At least I'd get more software support 1 year out than from the Android manufacturers ;).