Arguably, these vehicles do exist... in the form of 501(c)(3) university endowments. They endow professorships and graduate fellowships, pay for facility buildouts and infrastructure, and provide a strong pipeline of financial aid to allow talented undergraduates to pursue research rather than needing to repay debt immediately after graduation. And unused funds are invested in public and private markets, ensuring minimal waste and sustainable capital growth. And non-profit universities have strong and time-tested governance rules on many if not all of the dimensions specified.

But these very endowments have been special cased as additionally taxable, despite that status, under the 2025 OBBBA, resulting in research budget cuts [0].

Would independent endowments as you describe them be more immune?

[0] https://www.pbs.org/newshour/education/college-endowment-tax...