It looks to me like a "Nipoori" is simply a conventional BBQ with an unconventional conical hood. I would think that's a great idea for cooking things like chicken tikka, keebabs, etc.
However, it also looks to me like cooking these naans is the same as cooking them on a conventional BBQ (i.e. no hood and cooked on the grid). I suspect the "Nipoori", in the case, contributes nothing more than a conventional BBQ would contribute.
I sometimes use a BBQ to cook naans, but I prefer to use the solid, cast iron, plate and get it really hot. I think this simulates a "tava" pretty well.
For me, failing the availability of a pukka tandoor, I still think the best option is a quick "seal" on a medium hot tava (or BBQ flat plate) followed by cooking under a really hot grill.
I would agree with others' comments (in another thread) that, for the "Nipoori" to simulate a tandoor for cooking naans, it needs a wider "chimney" opening. Something for you to consider NP?