winget-cli-restsource VS winget-create

There is a way to point it to custom repositories, here's the documentation for that. They even have a repo with a template for hosting your own rest source here.

You can also stand up a private source. We have a reference implementation at https://github.com/microsoft/winget-cli-restsource. It's a bit tough to deploy presently, but we're making investments there. A PR is in progress with some PowerShell to make it easier to deploy.

Last but not least, They also released a reference implementation for the REST API source so you can host your private repository. This is a new type of source for the Windows Package Manager. The default source is a “PreIndexed” Package delivered via the Microsoft Store, but now you may add additional REST-based sources if they properly implement the JSON-based REST API schema.

This workflow uses Windows Package Manager Manifest Creator to update and submit a new version of a package manifest

Yes, any installer (MSIX, MSI, EXE) may be added (https://github.com/microsoft/winget-pkgs). There is even a new tool the Windows Package Manager Manifest Creator (https://github.com/microsoft/winget-create) to make it easier to build a manifest and submit it to the GitHub repository. Portable / Stanalone .exe files and .zip files aren't supported yet, but they are on the backlog.

You can also add your programs or packages by executing winget install wingetcreate to install the Windows Package Manager Manifest Creator. Once the tool has been installed, execute wingetcreate new provide the URL to the installer. Then the tool will download the installer, parse it to determine any of the manifest values available in the installer, and guide you through the process to generate a valid manifest. If you provide your GitHub credentials when prompted, it will even fork the repository, create a new branch, submit a pull request, and provide you the URL to track its progress.