Could I get some thoughts on which component is likely to go bad first when you apply too much voltage to a 5v flight controller?

After killing a FC (SP Racing F3 V1 wont power up anymore with battery or USB), I discovered that the "5v" PDB pad actually delivered closer to 11 volts!  I should have checked it with my meter before I assumed it was correct...lesson learned.

I'm wondering if I might salvage the FC by replacing some specific (if tiny) part...keep it or toss it?

It will be difficult to figure. I would try to look for burnt components under magnification. The second problem is figuring out what the component it is. For the price of the FC, it is s not worth it.

It's hard to say it all depends on the tolerance of the parts.
It's probably not a very good idea try fixing your FC by replacing SMD size components, it's a lot of work and no guarentee you can fix it.

I think its not worth it. Better buy a new F4 FC.