In my project, i can get the value of a variable defined inside a variable group like this, without no problem

steps:
      - checkout: none
      - bash: |
          echo $(shared-smtp-user)

But then, later in the code, i need to put into files the value of some variables from a variable group, and i do something like this

parameters:
    # The targetVariables to put inside secrets/, for example
    # targetVariables:
    # - shared-azure-devops-pat
    # - shared-ldap-password
    # - shared-ldap-user
    # - shared-smtp-user
  - name: targetVariables
    type: object

jobs:
  - job: echo_secret_files
    displayName: ????️ Echo secret files
    steps:
      - checkout: none
      - bash: |
          echo "Echoing targetVariables into secrets/"
          echo "using targetVariables ${{ convertToJson(parameters.targetVariables) }}"
          mkdir -p ./secrets/
          echo $(shared-smtp-user) # THIS WORKS !!!
        displayName: Display information about the secrets being used
      - ${{ each variableName in parameters.targetVariables }}:
          - bash: |
              echo $SECRET_VALUE > ./secrets/${variableName}.txt
            env:
              SECRET_VALUE: "$( ${{ variableName }} )" # THIS IS NOT WORKING!!!
            displayName: Generate file for ${{ variableName }}
      - bash: tree secrets/ -a
        displayName: Display the generated secrets

For some weird reason, i cant assing a value to SECRET_VALUE using this syntax "$( ${{ variableName }} )"

What im trying to do, for each item inside parameters.targetVariables, set the value of SECRET_VALUE to $(variableName), and then echo $SECRET_VALUE into a file.

Is there any way i can do $(myVariableNameHere), but without actually hardcoding myVariableNameHere, and instead using the variable from the each loop (called variableName)?