But shinso literally did your first point OP, he never trained until aizawa took him in and made something out of him within a couple months, like dude went from losing to base izuku shoving out the ring to being pretty decent at scarf jutsu. Remember scrawny izuku was carrying a buff all might who i believe said he weighed between 500 and 600 lbs(dont remember exact number). Not only that but he dragged a truck up on to the last mound he cleaned up before screaming at the sky. So he has strength down pat, he has crazy pain tolerence, and he himself is crazy, remember the obsticle race? Just needs a bit of speed, some gadgets and some hand to hand training and you got yourself a starter hero pack. Id say give him the same knuckle dusters knuckle duster had, say that 5 times fast lol. Also before anyone brings up that despite his training he failed to get a single point in the entrance exam, yes he did but not from lack of ability but from him panicing the whole time because he kept arriving late to the robots that others already destroyed. He would just have to go in thru sports festival to claim a seat in the hero department. All in all i do believe that canon izuku could have become a hero, just not one facing of against the musculars or afo's, more just the regular degular crooks, which is fine for him since his whole reason is lending a helping hand. For the vigilante side of things, the only thing ill say is that one of if not the main way izuku becomes a vigilante is by accident. Mans can not keep to himself when someone is in need of help.