-You vet engineers with however you/or individuals engineers see fit (test/ past work/ opensource / interviews/ etc), they highlight what they want + maybe what your data says would help them stand out for the "type" of dev they are.

- force companies to pay you $xk - $1xk to hire them right away if they "match" with someone they select, but with the ability to get a refund if they fire them within 3 months (but like 60 business days to get a refund, and allow them to keep picking but reset the window if they match with someone else again).

- keep in touch with those employees during that window

That way, companies will eventually get their money if they make a bad hire and still be willing to use you again, you can collect more data on the larger part of the employment life cycle and basically get 60 day interest free loans at worst.