The actual pace is so slow, tho. Will they ever find the kid’s bio dad?

We dont know there is no novel or anything

They already found the bio dad... Now they just have to kill him. His bio dad is the guy who killed Wolf King's younger brother and shot him in the first place.

Potato is very very loosely Wolf King's nephew. Potato is the illegitimate son of Wolf King's mentor/adopted father's biological son. His mom and Wolf King's brother were both killed in a turf war initiated by his dad, who is either awol or probably dead.