Using variables groups in Azure pieplines for Packer HCL2

I am new to Packer and went straight with HCL2 rather than json.

I manage to get the build working for Azure ARM builder for Windows and Powershell provisioner.

However, to secure my variables and make things automated for the end client, I need to use Azure DevOps Pipelines. In Azure pipelines I am struggling to use variables from the library group and pass them at cli. If I hardcode the values without passing var at CLI all works and image gets provisioned in Azure as expected.

I am not able to find any good examples for passing variable at CLI. Could you please provide a good source for reference.

Also I would like to know if the Packer marketplace task and Microsoft’s build immutable image task in Azure DevOps compatible with HCL2 as I am struggling to use them as well. Please advise.