When his unknown opponent suffers a brain haemorrhage in the ring at a local tournament, a rookie fighter must discover the boxer’s identity and find his family to gift his prize money to them.

There seems to be a disconnect between the character development and the outer goal. In most good stories the MC needs to overcome a character flaw, this process will make up the inner journey as a pre request for achieving the outer journey goal. In other words, your protagonist needs to change as a person before he can give them the prise money.

What character flaw does he have? How will he change?

This may seem like a small issue, but in this kind of story, you need a good inner journey. Otherwise, you've got a good guy doing a good thing with little to no obstacles - no conflict and no drama.

Why does the rookie have to give the prize money to the family? What is at stake if he doesn?t do it?

I like the premise, I think this could make a good road movie.

Your lead needs a partner, someone to go on the road with him.?

I feel, like I'd like to hear more about the journey and the obstacles there. Other than? not knowing where to find the family. At the moment, I'm picturing someone taking a flight, checking in in a youth hostel?and knocking at random doors.

"How hard could it be?" needs be cleared up in your logline. The 'implied conflict' must be reflected... This injury which happened in 'the ring', was then primered over TV right? How hard would it be to track them if they - after becoming aware of his injury - would try to reach him too?
If not, it needs to be cleared in the logline
Apart from that, it would be a heart touching film
Good Luck!