The ms-appinstaller protocol has been disabled.

To anyone else facing implementing a workaround and is using Azure pipelines:

here is a yaml task that will edit the generated html to remove the protocol and include explicit instructions that the button will cause a download, and the downloaded file should be run.

Anonymized example from my implementation:

And here is the task:

    - task: PowerShell@2
      inputs:
        targetType: 'inline'
        script: |
          $x = gci -Recurse *.html
          $page = get-content $x
          $newpage = $page |  foreach { [regex]::Replace( $_,'ms-appinstaller\:\?source\=','' ) }
          $newpage = $newpage |  foreach { [regex]::Replace( $_,'(<div class.*app-description[^<]*</div>)','$1'+[System.Environment]::NewLine+'<div class="insert instructions"><p style="color:red" >Installation instructions:<br>1. Click the install button to begin download of installer file<br>2. After download completes run installer file to install application</p></div>' ) }
          set-content $x -Value $newpage

Note that there may be more efficient ways of accomplishing this, but I went with what I knew and could make generic.