i can't recall definitive answers on the subject of paying players and it's not an easy search for me-
would love to have absolute clarification-
my limited understanding of paying non-scholarship players (walk-ons/other) NIL is that yes, you can.
the only caveat at the moment is that Schools have strictly defined, limited coordination with NIL Collectives.
if correct, then yes, walk-ons can be paid with NIL as well as any other player. i have no clue of the amount limits, IF any, or what/how much obligation the players have in exchange.
the point is that the 13 scholarship limit rule may be, at the moment and for the most part, irrelevant. if i recall, there is a total floor roster limit in some variation or another.