This is essentially a docker/container image whereas the public repository contains code for the Azure VM images.

github-hosted runners execute the workflows in virtual machines hosted in Azure.

If you intend to use the same VM images repository, then you need to set the VM infrastructure in Azure and deploy your VM with images generated from the repository.

However, for containerized self-hosted runner you need to create your own docker images, the public github runner images repository can only provide you with the software that you may intend to install in your image.