(a) Any person under 18 years of age who possesses or goes armed with a dangerous weapon is guilty of a Class A misdemeanor
(c) This section applies only to a person under 18 years of age who possesses or is armed with a rifle or a shotgun if the person is in violation of s. 941.28 or is not in compliance with ss. 29.304 and 29.593. This section applies only to an adult who
transfers a firearm to a person under 18 years of age if the person under 18 years of age is not in compliance with ss. 29.304 and 29.593 or to an adult who is in violation of s. 941.28.
the question - can a 17-year-old open carry a long gun in an urban setting is settled by 948.60 2a - the answer is no.
All exceptions are in a hunting context (or military training etc.)
It spells out ONLY IN A HUNTING context the rights of 16 year-olds and younger people to carry guns.
Since 17 year-olds aren't mentioned - they either have no rights or have all the rights of a 16 year old. There doesn't seem to be any way to derive that their rights are the same as that of 18 year olds. Even if true - it only pertains to hunting.