You "source" parts for a machine or boxes of cereal for a store. "Sourcing" people communicates perfectly how you think of them: interchangeable resources.<p>Matching people based on "tech stacks" rather than building a team that multiplies individual talents describes poor hiring priorities. Ideally hiring focuses on adding business value and finding people aligned with the product or service goals, not on languages and tools. Smart and gets things done, as Joel Spolsky aptly put it. Not "has React on resume." Try using an AI. Good luck.
I would often put out feelers on upwork, asking for a 1 hour project in the expertise area. Interview 100 people, hire (for the hour) 10, make offers to the top 1 or 2.