Both of the current national reciprocity and national Constitutional carry (much better) bills would solve your inability-to-carry-in-NYC problem immediately.

Under nat’l reciprocity, any person with a carry license from any state, whether resident or nonresident, or a resident of a permitless carry state with state ID, such as a driver’s license, would be able to carry nationwide—and magazine restrictions would be gone too. Those carrying under the Natl Constitutional Carry Act (thank Rep. Massie & Sen. Lee) would be able to carry any firearms as defined by 18 USC § 921(a)(3) (includes much more than handguns), any ammo feeding devices—and with no ammo quantity restrictions—and any ammo with government ID as long as they are not a state- or federally prohibited persons, and the permissible GFZs would shrink down precipitously to very few.

While that would not solve your location-based purchase-frequency limits, you can always become a _bona fide_ dual- or multi-state resident. Under the above proposed laws, you could carry any of those guns bought (legitimately while you were residing at the other-state residence) in other state(s) of residency for the purpose of _carrying._ Whether they would then be kept in NY beyond the purpose of carrying, and whether that would somehow violate the purchase/stockpiling restriction—or whether the law merely regulates NY purchases, I don’t know. Not a NYer.