Issue - On upload of app (.sppkg) file, App package not getting valid. On uploading, it is expected to SharePoint will display a dialog and ask you to trust the client-side solution to deploy.
However, popup is not coming. Also, Product ID is also blank
Reason - Your Tenant is not a Developer Tenant. SharePoint Framework is not available in production environment, so the only way you have to test it, is using a dev tenant.
- Follow the steps to create a new Office 365 Developer Tenant - https://dev.office.com/sharepoint/docs/spfx/set-up-your-developer-tenant
- Convert existing tenant to Developer Tenant - Make sure you have First Release options enabled.
After updating First Release settings, it may take a while to update the settings. Once updated, your tenancy would have SharePoint Framework Release enabled and App Packages will function as required.