This is the function of the fiscal sponsorship program at NumFOCUS. All fiscally sponsored projects basically come under the umbrella of NumFOCUS' nonprofit status, so that the projects can receive tax-deductible contributions, etc.
NumPy joined NumFOCUS as a fiscally sponsored project in 2015, so it's been eligible to receive donations as a non-profit (because of NumFOCUS' nonprofit status) since then.