Definitely, proprietary software should be supported. You could either let developers upload the binary directly, or just not offer sources to download for users, optionally deleting them after they have been built.
Debian has developed an amazing set of standards for software repositories which I think should be applied universally to all package management ecosystems that want to have open source at their core.
E.g. they require that the source code has to be actual source code, aka "preferred form of modification" and not something minified. They also have separate repositories for proprietary and DFSG-free software, allowing users to choose whether they want to use proprietary software or not. Also, they run their builds without internet access, so the source code (as well as the dependencies tracked by the system) is actually everything needed.
Debian has developed an amazing set of standards for software repositories which I think should be applied universally to all package management ecosystems that want to have open source at their core.
E.g. they require that the source code has to be actual source code, aka "preferred form of modification" and not something minified. They also have separate repositories for proprietary and DFSG-free software, allowing users to choose whether they want to use proprietary software or not. Also, they run their builds without internet access, so the source code (as well as the dependencies tracked by the system) is actually everything needed.