The trap would be spending $5000 on a drone that you don't realize doesn't have a standard DJI warranty nor DJI Care. As for grey market, it a common term for items, and I see it a lot in electronics/cameras... For example, A seller gets an...
Are you using a sim designed for aerial usage. Here in the uk to get the best reception you need the right sim otherwise the tower the drone will select is not optimum and can often be worse than just using the o4 connection.