I’m leery about a percentage just because I perceive a conflict of interest. Overall compensation of 10% might be about right, but tying actual compensation to the cost of stuff that is bought creates a perverse incentive to overspend on things. That’s money donated for the betterment of humanity, not so I can have a 3 acre swimming pool.
But IDK maybe I’m looking at it wrong.
I think you are looking at it kind of wrong, in that: with a savvy board, the first savvy thing they would do, would be to guarantee their own self-benefit, going head first into a conflict of interest… meaning you can’t have a project like that driven by a savvy board, instead you need an altruistic, idealistic, etc. board… but then, a non-savvy board, would be much likely to just squander the money, or get swindled out of it, so… I don’t think a project like that would ever work as expected.