Looks like the CVA files one can get by swapping action:install to action:download, and specifying /softpaqdownloadfolder:, which contains the value "SystemMustBeRebooted=1" with things that need restart.

Just then need to parse these CVA files, and leave these to last, and provide prompting to user. Suggest Powershell for this, but if don't also want to deal with signing the script, or other ways to get around ExecutionPolicy, VBS could also be used with more code.