The MSM says there are hundreds of islands in the Andaman & Nicobar islands. That is true, but most are not big enough to land an airliner.
That cuts the search area down considerably if a hijacking is the theory.
If the idea was to swipe an aircraft and repurpose it, then the landing zone would have to have a landing strip with an improved surface (paved, and paved thickly). You can’t hide those. Additionally, fuel would have to be shipped in because it’s not likely they could get this bird off the ground again without it.
I wonder where they would get the fuel? Is there a Chevron station nearby? Would we be able to trace the credit card? It’s possible they pre-positioned the fuel, I suppose.