For attacking an enemy that doesn't have and real air defences they shouldn't be using a multirole jet fighter like the F-35 or a jet ground attack aircraft like the A-10. They're both way too expensive to run.
They should be using a counter-insurgency aircraft, like the A-26s the Afghan Air Force is about to receive.
Not having a real air force is not the same as not having real air defenses. And the A-10 may be a juicy target for air superiority fighters, it's very resilient against ground-based firepower.
Low and slow the A-10 can out turn just about all air superiority fighters (vectored thrust fighters being the largest exception); as the old saying goes "get down low and go go go". The true enemy of planes like the A-10 is 4th+ gen missiles combined with look down radar.
They should be using a counter-insurgency aircraft, like the A-26s the Afghan Air Force is about to receive.