In order to view what public SSH key your Azure virtual machine is using or some other OS details like the admin username of your machine, you can use:

az vm show --resource-group YourResourceGroup --name YourVMName --query "osProfile"

If you need to know what’s the admin username of a particular Azure virtual machine, use:

az vm show --resource-group YourResourceGroup --name YourVMName --query "osProfile.adminUsername"