As Verizon has different LTE-bands, I need to ask: How does the modem decide, which band to use, assuming, service “vzwinternet” available ?
By negotiation with the base station, using various parameters including signal strength and quality, and the band priorities broadcast by Verizon.
Much of what you see in the AT+QENG="neighbourcell" result is regularly transmitted from modem to base station.
Selection is done by the combination of Physical Cell ID and EARFCN (which combination must uniquely identify a cell in view at any time). The band is determined along the way by that process.
This is my understanding.