The world could run on older hardware if software optimization was a priority

Is there or could we make an iPhone-like that runs 100x slower than conventional phones but uses much less energy, so it powers itself on solar? It would be good for the environment and useful in survival situations.

Or could we make a phone that runs 100x slower but is much cheaper? If it also runs on solar it would be useful in third-world countries.

Processors are more than fast enough for most tasks nowadays; more speed is still useful, but I think improving price and power consumption is more important. Also cheaper E-ink displays, which are much better for your eyes, more visible outside, and use less power than LEDs.