upgrading firmware for galaxy Note 5(SM-N920V)

Hello All,
I have a factory unlocked samsung galaxy note 5 from verizon(SM-N920V) which has android 5.1.1 OS. I want to upgrade to android 7.0. please advise if i will need to unlock phone again after the upgrade. Also assist if i can upgrade with any firmware other than that of verizon, let say any non-carrier based firmware(eg. SM-N920K or SM-N920I etc).

Regards
Brainy

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