Hard to do without a substantial seed for the fund. A $1,000,000 gift can distribute $50,000/yr at a 5% distribution rate. The largest NIL's currently are spending $10MM+/year. I agree a fund would be better long-term, but with how volatile the NCAA/rules are currently, substituting the $1,000,000 for NIL use THIS YEAR will probably impact much more positively than trying to do a 5% distribution. 5-10 years from now, NIL may look completely different (if it even exists). Now, if we had a $100,000,000 gift that could distribute $5,000,000/year, that would be massively impactful right now (and I'd be willing to bet that individual would keep the funds in their name and donate the distributions to NIL every year, instead of endowing the full $100MM).
EDIT: I think a similar effect would be to set up an endowment with the DSO and/or the school directly. Funding athletic scholarships can impact athletics similarly, by allowing other resources to go towards facilities/CoL payments. The wealthiest schools have all of their back of house payments taken care of, and can direct their alumni to donate (almost) exclusively towards NIL. I do not think USF is in that position yet, as we can really use the money to pay for stadium, increase coaching pools, etc.