In my opinion...
1) it should be single engine medium aircraft. This would serve as a replacement for the older blocks of F16s and JF17s.
2) Avionics should either be domestic or sourced from the corresponding country(Turkey in case Pak buys TFX or China in case Pak goes for J31 or something like that). This should be done for the sake of commonality. Also AESA is a must.
3) No expense should be spared in making it stealth. This includes the shaping, composites, and RAM. Stealth is a huge advantage over the enemy.
4) knowing the constraints of Pak's economy...the savings could come from excluding TVC. TVC is costly...and for this single engine medium aircraft, which will become the next mainstay of the PAF(replacing JF17s and F16s gradually)...TVC would be an overkill and an unnecessary expense. Instead it could have canards to achieve high AoA...if those wouldn't effect its RCS too much.
Another aspect of savings would come from the fact that it's a single engine jet. This aircraft would not be intended for air superiority. For air superiority Pak can acquire off the shelf(or with some ToT) jets like TFX or J31 or something. This single engine jet would instead be multirole(including ground attack).
Some commonality of avionics or engine between this single engine 5th gen jet(Project Azm) and the twin engine(tip of the spear and lesser in numbers) 5th gen jet(TFX/J31/etc) would be immensely helpful. This commonality could reduce the cost, make maintainence easier, and improve aircraft availability rates.
Moreover this single engine medium 5th gen jet can be a huge success in terms of exports. There is currently only one single engine 5th gen jet(F35)...but it's not a medium jet. Additionally it comes with a ton of strings attached with the possibility of sanctions in war time...not to mention the huge cost, putting it out of reach for most countries. So in short Pak can corner the market in the absence of any competition in that category. After the next 10 to 15 years when the time rolls around for other nations that are not particularly rich to upgrade their jets, they would consider 5th gen jets. A single engine medium 5th gen jet(less costly to buy, fly, and maintain as compared to twin engine bigger 5th gen jets) with no strings attached and a modest price(if Pak can control cost over runs) would be a very appealing option.
End goal should be for Pak to only have two platforms that serve as a high/low mix. One being the rather expensive heavy twin engine 5th gen jet(for deep strike capabilities and air superiority) and the other being the lower cost medium single engine 5th gen jet(for being the workhorse and to make up numbers). It would be much easier to just have two types of fighter jets in terms of supply lines and maintenance facilities, especially if there is commonality between the two.
Before anyone gets all riled up...do know that this is just my opinion. I don't know if this is the path Pak would follow or if it's even achievable for Pak to be able to fund a clean sheet design like this.
