Can Rose Tico's target lock be used on the same attack it is acquired on?

I see no reason why you wouldn't be able to do so.

Yes.

Can Rose Tico spend a result to acquire a lock, reroll dice, then spend ANOTHER result to acquire ANOTHER lock for a future attack? My gut says no, because of the once-per-opportunity situation applying to "while you... perform an attack."

33 minutes ago, emeraldbeacon said:

Can Rose Tico spend a result to acquire a lock, reroll dice, then spend ANOTHER result to acquire ANOTHER lock for a future attack? My gut says no, because of the once-per-opportunity situation applying to "while you... perform an attack."

Your gut is correct.

My gut is hungry for nachos...