Damn that is a lot of acid damage to the mobo... its crawled its way to many IC and sockets
so sad to see a A500+ in this condition.
The Gary chip should be okay, the socket might clean up well without needing to replace. A thin stiff brush and alcohol to clean away all the mess. The resisters on the right hand side of the removed battery look bad, maybe if you going to resolder a Gary socket you should replace these as well.
Best of luck! Hope you can revive this poor Miggy
Az