Here's a scenario:
HS athlete is a once in a generation QB, 6'9" do-it-all forward, whatever. Clearly the top prep player in the nation in his sport. CEO of a nationally known insurance company (or auto maker, restaurant chain or widget manufacturer) believes it would be beneficial to lock this kid up in an ad campaign. Being a brand known coast-to-coast, this CEO also feels he'd get that much more bang for his buck if said athlete also wore a Duke (or UCLA, or Kentucky) uniform in the ads. The firm (or through accountant mumbo-jumbo, the CEO) donates $4 million to Dukes' NIL fund. By sheer coincidence, Duke proceeds to outbid the next highest offer by, oh, say 3.5 million & the kid signs.
I don't see anything that prevents this.