But even if Wyll did make it all up
Thats the thing ...
I dont think he did.

Its more like ...
Well, i just love stories about tricksters ... that will fullfill your wish, just never in the way you would like it.

What i would like would be something like:
Wyll had one wish from Myzora, in return ... he would seal pact with her.
His wish was "i want to be a hero" ...
And so SHE by her own malevolent will, made him "a hero" by spreading false tales about his heroic deeds.
But he would find out (sooner or later) that he actualy like being called a hero, so he travels the world trying to live up the legend she created for him ... and so far, failing horribly ... bcs he still dont understand that true hero doesnt do what they do for fame and glory.

Such characters are perfect for tragic end, when they finaly do some selfless act (usualy self-sacrifice), just for the sake of actual good ... and not their own gain.

I wonder if i can find any example ...
Prince Lir, from Last Unicorn movie ... that would be quite close.