I'm specifically wondering about the depictions of Beggar So in popular culture, such as his portrayal by the inimitable Yuen Siu-tien. For instance:
Li Tienguai has a magic medicine gourd; Beggar So is often depicted with a wine gourd.
Li Tienguai was said to have transmigrated into the body of a beggar.
Both Li and So are itinerant.
Any information on this subject is welcome, including from the oral tradition.
I find this subject extraordinarily interesting because Chinese cinema seems to provide a unique, documentable look into how historical and semi-historical figures are mythologized over the course of a few generations. I suspect it's a process similar to the formation of the Icelandic Sagas, both in terms of time-span from history to legend, and in taking shape in the context of new medium (i.e. prose narrative in the case of the sagas.)
Wong Fei-hung is obviously the leading example. Unlike Beggar So, we we can actually trace Wong's the lineage from the historical person to his student, Lam Sai-Wing, to Lam's student to Lau Cham, who then appears in the Kwan Tak-Hing series playing his real-life Sifu, Lam. Lau Cham is, of course, the father of Lau Kar-leung, who himself directed multiple films about his "great-grand-Sifu". (Both the Laus and the Yuens were enormously influential choreography families, and both spawned significant directors in the Kung Fu movie genre, Yuen Woo-ping, the son of Yuen Siu-tien, being perhaps the most famous.)
For those not familiar with this material, it's a pretty safe bet that there have been more movies made about Wong Fei-hung than all of the Western superhero movies combined. I feel I have to strongly make the point that this is NOT "fictional mythology" such as with genre literature, but real mythology forming in modern and contemporary times. As far as I can tell, there is nothing in the West with this scope or scale--Kwan is said to have played Wong in excess of 70 times, and he's just one actor. Although there are far too many films about Wong to name, he was notably portrayed by Jet Li in numerous films, and likewise by Jackie Chan in his famous Drunken Master series, incidentally co-starring with Yuen Siu-tien as Beggar So in the first installment.