Creating a dropdown for Timezone

I am trying to create a “Customer” collection and one item I want is for them to be able to select their timezone.

This is becoming rather difficult because:

  1. I can not add “name” and “value” to dropdown and it has to be value
  2. I can not add a value like this: “+2:00” or “-3:30”, because it needs to start with alphanumberic and I think it doesn’t allow symbols

What would be the right way to approach this?