According to Vex rule R7 part c, “c. Any commercially available #4, #6, #8, M2, M2.5, M3 or M4 screw up to 2” long, and any commercially available nut and/or washer to fit these screws," would wingnuts count as a ‘commercially available nut’?
Yes, wingnuts would be allowed by <R7c> as long as they meet all other criteria listed in the rule.