Probably what I'd rather have is a phone that has a low power low function mode, that I can configure what apps are available, and then a regular mode where everything is available. But to get to it, I need to convince a LLM equivalent of Seinfeld's soup nazi why I need it.
Isn't this literally already built into Android? Extreme Battery Saver effectively turns your phone into a feature phone, disabling every app except Clock, Phone, Messages, Settings, the Play Store, and your camera. And you can add other essential apps to the whitelist (e.g. I have my note taking, ride sharing, banking/wallet, calendar and TOTP apps enabled, and my music player if I'm on the go). It even degrades the phone's performance to match lol, and the added battery life you get from it is fantastic.
Might be a Pixel-only thing now that I think of it...then again I'm pretty sure other OEMs like Samsung would have their own versions