No idea if it's legit, but a poster on 247 explained the way places are structuring NIL to not be completely blowing off the rules. He said there are two different ways it goes:
In appearance-based setups, the money may not necessarily be up front but it is contractually guaranteed. All the player has to do is show up the Friday before every game at the team hotel or whatever, and sign some things. This has built in protection for the collective, because if the player transfers out, he won't be at the team hotel and therefore won't get paid. I assume they just tell the recruit the deal is for a million or whatever, and you get it in installments for each appearance.
The rights based model is what he says A&M does, which is the collective buys the players marketing rights up front, so there is an immediate payment to some degree. Then the collective arranges for marketing opportunities and more money. Since the collective owns the marketing rights, if the player leaves, the collective will just not book them any marketing opportunities. The legality of this method is debatable.