Has this been invented? (See description)

ummmmm you mean an inverter? The power source has to pull from somewhere and it would be limited in its output.
They have them for cars.
Or maybe this

An Uninterpretable Power Supply (UPS) is a battery, with outlets, designed to take over when your power goes out..

Little ones which can power a computer are less than $100.
Example

If you’re charging an electronic device using a wall transformer, it’s very inefficient to convert DC to 120 VAC then back to DC—though admittedly it would work for light loads.

a portable generator has been invented… put into the wall? thats new… like a hospitals generator powering the I.C.U.

Solar powered generator. It uses the suns rays to fill up batteries. You can then run a cord from those batteries to run the tv, lights and cell phone charger. We use one at one of our cabins. Works a treat.

a generator has been invented and what do you mean by putting it in the wall? do mean hanging it?