Two different questions here:

For old, discarded devices: It is the conjunction of Moore law and programmed obsolescence that makes this unsolvable on any large scale.

Suppose that Android was modular, not ara-phone-modular, but almost custom-built-pc-modular (+long term software updates). will you replace it that fast in the first place ?

For new devices: The waste/potential is rather on the "software level", not the compute one: These are 2 very different things. It is not the CPU meter that matters.

And you know what, 20 years ago I was hopeful that a lot of people in 2020 will be using their computer more creatively. I was naive of course: If you are not a curious person to start with, computers will rarely make you so.