Pony currently handles installation of first-gen packages.
You can find first-gen packages in the file data/groups/packages.json.
This file is a simple JSON which maps a name of a package group to
a list of package definitions.
Each package definition has to include at least SubscriberPackageName and SubscriberPackageVersionId.
If you have some org with all packages installed, use sfdx pony:package:group:export to create this file.
This command automatically removes standard packages,
please open an issue if some standard package is not removed.
{
"default": [
{
"SubscriberPackageName": "Package Name",
"SubscriberPackageVersionId": "04t..."
}
]
}