I don't know a lot about Turkeys so will tag in
@Huntmaster and
@R2elk to see if they have any suggestions.
Does his wing droop all the time as well or he uses it to balance?
To me, the leg looks to be a leg bone deformity. Valgus Varus, with your boy having Valgus Deviation.
Sadly, if it is a leg bone deformity, you would not be able to correct it.
Some birds (chickens) can learn to adapt and thrive if the leg does not get much worse than what is in your photo. Some are not able to get to food/water and of course as they get older and gain weight, the leg is not strong enough to support them.
I would say the same would be for a Turkey.
Wrapping the leg to offer some added support may help, but I think that would be a lifetime commitment on your part.
I'm sorry, I wish I knew more, hopefully the others have better suggestions.
