> Foldable phones still feel like a novelty that is expensive and fragile, among other tradeoffs.

I've had a Moto Razr Pro for three years now. No signs of wearing out and it's taken quite a bit of abuse. The only tradeoff is probably water resistance and the crease in the screen (which you get used to but is a trade-off). The positive: same size a a wallet when folded, outer screen makes checking notifications fast, and the outer screen lets you use the outer camera for selfies and video recording. I'll probably get another one when the battery dwindles away.