Considering the requirements:
- maintain a uniform configuration for virtual machines
- minimize administrative effort
To mantain the configuration status of a VM you must use DSC.
To minimize the effort of creating the VM you can use an ARM template so that you can reuse it for each VM. Deployment groups requires more effort.
https://docs.microsoft.com/en-us/azure/virtual-machines/extensions/dsc-template
https://docs.microsoft.com/en-us/azure/devops/pipelines/release/deployment- groups/?view=azure-devops