The real answer? Buy a phone older than the 15. You’ll never get on-device intelligence. My 13 Mini takes great pictures, performs perfectly, has great battery life as a non-gamer. And it should get at least 3 more years of iOS updates (maybe more? phone specs have really leveled off).
Anything newer, Apple and Google will start pushing intelligence on you simply because your phone can do it.
You could try GrapheneOS as well on a recent Pixel.
Longevity is worse than non-folding phones, simply because the hinge and folding screen are wear parts.
Camera is worse, because there’s less z-distance for lens depth. If they push it with a bigger camera bump, you wind up with a maximum thickness of easily over 15mm very quickly, even if the rest of the phone is thin, that hurts.
Battery life is worse, because two separate batteries with puncture protection, folding screen, digitizer, etc in between are heavier and less power-dense than a single large battery.
And the price is higher because there’s more screen, more batteries, more materials, and more R&D to pay back in the hinge and fold mech.
The Z flip is the most tempting to me simply because the height and width are far more attractive than current monster-sized phones. But it’s disingenuous to pretend the plastic inner screen (yes, that’s literally what that top layer is, not glass), the cost, the inferior battery, and the inferior camera aren’t serious compromises.
And all for what? So I can have a giant inner screen? I think my (smaller than any modern phone) phone is already too large, too addicting, and too tough to use with one hand. For serious tasks and videos I use my laptop.
I believe it is awesome for you. But there are downsides.
Honestly I wish Kagi would build their own full Firefox fork and maintain it independently. I already pay for search, I wouldn’t mind paying for my browser if it actually respected me!