In order to buy peace, Afghanistan should enter into a pact with pashtuns and give them certain areas with greater autonomy and special status like Kashmir in India. Afghanistan can put a condition that pashtuns dominated areas should also be brought under the fold of Afghanistan.
There is a saying in hindi "Apni deewar bhale hi gir jaye, padosi ki bhains marni chahiye"
The problem isn't Pashtun nationalism - it is the exact opposite, the LACK of Pashtun nationalism. That is why Punjabi Porki pigs can use Pashtun against Pashtun by brainwashing one against the other under the umbrella of "ummah".
Right now the problem is that Porki Pashtuns are still rather nationalistic about Porkistan because they don't know what's happening to their brothers in KP and FATA - the ISI keeps a very tight check on the country finding out about the truth of the remote areas in KP, FATA, Balochistan, etc. There are more Pashtuns in Pakistan than in Afghanistan.
India needs to start a full on propaganda war, revive Bacha Khan's image and symbolism, and spread the message of Pashtun nationalism far and wide. The fact that the Porki deep state is getting more and more paranoid and abducting, banning, bombing their own citizens with increasing frequency means that it's losing grip. Once ISPR loses the narrative, the country is finished.
If Pashtuns unite across both sides of the Durand line, Porkistan's pork is cooked.