Winapp package
Skill microsoft/winappCli/plugins/winapp/skills/winapp-package
winapp, the Windows App Development CLI, is a single command-line interface for managing Windows SDKs, packaging, generating app identity, manifests, certificates, and using build tools with any app framework.From the repository description
npx -y skills add microsoft/winappCli --skill winapp-packageAssembled from the repository path, not quoted from the project. Check it against their README if it does not work.