The ESD Association’s Resistance-to-Ground (Rtg) requirement for an operator wearing a wrist strap is < 3.5 X 107 ohms (ANSI/ESD S20.20) . A wireless wrist strap will never meet this requirement.
Wireless wrist straps claim to work by “making (a) body’s static electricity to discharge through discharge box.” Assuming that an operator was tribocharged to 10 KiloVolt and wearing the “wireless” wrist strap, it would take many hours (days even depending on the ambient relative humidity) to get you below 5 KiloVolt, never the less 10 Volts. Most (if not all) of the charge reduction would be due to natural recombination of the charges on your skin (and now metal casing of your “wireless” wrist strap) with the air molecules and the natural conductance of the air through water vapor content (relative humidity).
You could get the same effect of a wireless wrist strap by cutting your hair to about 1/4″ long and then putting conductive jell in your hair (The guys over at the ESD Journal have another solution too). The ends of your now conductive hair would act like corona discharge points at extremely high voltages to bleed current into the air or help to enhance the natural recombination process. The fact that your hair would need to come in very close proximity [0.1 to 1.5 inches] to ground or any other potential with at least a 3 KiloVolt difference (due to the dielectric strength of air) or enhancing the natural conductivity of the air needs to be considered to even get you down below a few KiloVolt.