yeah the gentle fist is called that because it doesn't do physical damage it's a precise attack that injects chakra into the chakra network to inflict damage to the organs or to benefit the target's chakra or heal them (I guess kind of like acupuncture) although I do note that neji using the 8 trigrams 64 palms attack destroyed a whole tree with the rate of attack and with only chakra so it's not that it's impossible to do physical damage entirely it's just a martial arts designed for taking advantage of the chakra network of someone and using the byakugan. if i remember hinata also damaged some creature that was a part of the ten tails (i think?) and I have no idea if they have chakra networks ( i really don't like the war arc and their mud enemies). either way gentle fist doesn't seem likely to hurt anyone with enhanced durability like superman and it shouldn't do anything internally unless superman has a chakra network. if you want to do physical damage with chakra better to increase your strength like how sakura and tsunade's jutsu work and how sasuke thought lee stopped his kick. also if you mean hinata specifically I don't know if i would give her neji's level of skill since he was sort of a genius even at 13 while hinata's repertoire is fainting and being unable to defeat an alien who kidnapped her
So hinata is basically useless against those that don't have charka and yes I'm talking hinata herself no help from anyone
OK how about mira and erza from fairy tail, nami and Robin from one piece and Mikasa?Gentle Fist isn't hurting Wonder Woman or Ms. Marvel. She will break her wrist trying that kitten on either of them.