Convincing reasons for the internal open source service of a highly recognized brand just by downloading the sources?

Suppose you are considering opening a great service of your internal business infrastructure. Let's say you have the necessary resources to ensure that the minimum requirements are met: licenses are ordered, blasphemies are eliminated, security audits are performed and all known security vulnerabilities are corrected. Let's suppose that your company that makes the open-sourcing has a very recognized and valuable global brand.

Does it make sense to open this type of service simply by dumping the files? I suppose that here it will not even be possible to run the service as it is, because it will have dependencies in other systems, not open source.

If not, what would be the minimum effort required to make it worth the open supply?

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