My research indicates the the DOOR REQUEST SWITCH (the lock/unlock button on the doors handles) can be set to OFF/HORN/BUZZER. BUZZER is the Intelligent Key beep that I assume is default (it has been on every Z that I know of). However, the FSM only indicates these can be changed via dealer software. Hopefully, there is a DIY solution.
I emailed the head tech at the dealer where my car is currently having some warranty work done, and he already responded saying that he would do his best to reply by the end of the day. I appealed to them as the only Nissan dealer left in the greater Austin area with the chance to earn my recommendation as a competent dealer, and that I would like to be able to steer other members of the Z community towards a dealer that I trust. I'll follow up as soon as I hear something back