Variable Syntax in Azure DevOps YAML Pipeline with Each Loop

I am trying to figure out the syntax to be able to reference a variable within an each loop and replace it with the loop variable.

Here is a very simple example of what I am trying to do.

trigger:
  branches:
    include:
      - develop

variables:
  - name: regions
    value: ncus,scus
  - name: webAppName
    value: myapp-<region>

stages:
- stage:
  jobs:
  - ${{ each region in split(variables.regions, ',') }}:
    - job:
      pool:
        vmImage: 'windows-latest'
      steps:
      - script: 'echo "replace(webAppName, <region>, region)"'

What I want is the output of the echo statement in the script task to be myapp-ncus and myapp-scus. I know the syntax I have here is incorrect, I just wanted to give some pseudocode representation of what I am trying to do. I've tried all combinations of $(), ${{ }}, $[], but nothing seems to work.

Edit 1

Let me clarify the issue. The trouble I am having is specifically around the replace operation and trying to reference the loop variable in that replace operation. I know I can very easily reference the loop variable like this:

- script: 'echo ${{ region }}'

But I need to do a string replacement in the webAppName variable with the region loop variable. Here is a terrible attempt that doesn't work:

- script: 'echo ${{ replace(variables['webAppName'], '<region>', ${{ region }}) }}'

The issue I am having trouble with is doing the replace in a pipeline variable with the loop variable.

Example 1 - using replace function

trigger: none

pool:
  vmImage: 'ubuntu-latest'

variables:
  - name: regions
    value: ncus,scus

  - name: webAppName
    value: myapp-<region>

stages:
- stage:
  jobs:
  - ${{ each region in split(variables.regions, ',') }}:
    - job: ${{ region }}
      variables:
        - name: webApp
          value: ${{ replace(variables.webAppName, '<region>', region) }}
      steps:
        - checkout: none
        - script: |
            echo "Deploying to $(webApp)"
          displayName: Deploy to $(webApp)

Running the pipeline:

Example 2 - using an app name prefix

trigger: none

pool:
  vmImage: 'ubuntu-latest'

variables:
  - name: regions
    value: ncus,scus

  - name: webAppPrefix
    value: myapp-

stages:
- stage:
  jobs:
  - ${{ each region in split(variables.regions, ',') }}:
    - job: ${{ region }}
      variables:
        - name: webApp
          value: '${{ variables.webAppPrefix }}${{ region }}'
      steps:
        - checkout: none
        - script: |
            echo "Deploying to $(webApp)"
          displayName: Deploy to $(webApp)

Running the pipeline: