Button-card entity variable

Hi

I have a input_select helper with entity id in state, like light.office

It is set by automation, when a button-card turns on the light, the entity id is set in the input_select and that works.

Next i like a button-card to show the information from the input_select.light state as entity in the button-card.

my simple button-card for test

type: custom:button-card
variables:
  my_entity: '{{ states('input_select.light') }}'
entity: '[[[ return variables.my_entity ]]]'

This will give me the input_select

my_entity: 'input_select.light_controller'

This dos not work:

my_entity: '[[[return states('input_select.light_controller') ]]]'

The plan is to have a button-card in my dashboard with custom_fields that shows light color and brightness and will change when another light is turn on.