"They will then use that showcase as part of the sales-pitch for GitHub Enterprise" This is pretty much how everybody does it when it comes to enterprise sales

"They will then use that showcase as part of the sales-pitch for GitHub Enterprise" This is pretty much how everybody does it when it comes to enterprise sales. Even massive companies like IBM have partners to fill in gaps in their product line. When it comes to enterprise sales, you don't go in with an minimum viable product, you go in with a Swiss army knife. There is a reason why Jira is the way that it is. By making it easier for others to develop enterprise grade solutions that is tightly integrated with their own, they can say to potential customers "GitHub Enterprise doesn't do that but we work with a company that does". All it takes is one missing feature for a customer to say no, because they usually have the resources to build it in house. Or superglue together a solution that is ugly, but meets the needs of one or more individuals in the purchasing chain.