riddle - I can signal the demise of the world, or I may be the key to unlocking it

I may have four legs, or I may have none-
I may have two ears, but perhaps I cannot hear.
I may have two eyes, but could it be that I cannot see?

Either way, I can be found in your home;
Either way, something trails behind me.

Either way, some may touch me while others refuse.

Maybe I can eat, but maybe I cannot.
Maybe I rely on shadow, but perhaps I rely on light.
Maybe I am scorned, but I can also be loved.

I can signal the demise of the world,
Or I may be the key to unlocking it.
Do you know of whom my tale speaks?

Answer

You might be a

Mouse (small mammal)

but maybe you are a

Mouse (computer accessory)

I may have four legs, or I may have none-
I may have two ears, but perhaps I cannot hear.
I may have two eyes, but could it be that I cannot see?

the first possibility always refers to the mammal, the second to the computer mouse

Either way, I can be found in your home;

OP probably lives somewhere where mouse infestations are more common

Either way, something trails behind me.

tail or cord

Either way, some may touch me while others refuse.

mice (especially the furry ones) scare some people

Maybe I can eat, but maybe I cannot.

same pattern as before

Maybe I rely on shadow, but perhaps I rely on light.

mice hide in the darkness, an optical mouse uses light to detect its position

Maybe I am scorned, but I can also be loved.

mice are considered pests, but sometimes kept as pets

I can signal the demise of the world,

rats and mice seem to have taken cities over in almost every post-apocalyptic movie

Or I may be the key to unlocking it.

https://www.youtube.com/watch?v=vXgXA4VlStE

Do you know of whom my tale speaks?

Not really, no.