Question about switching

Hello everyone my fiance and I use Verizon we absolutely hate it nothing but issues with carrier calls and internet keep going out. She has a iPhone 17 pro max and I have a pixel 10 pro xl and we were wondering how long it would take to get the 800 virtual gift card we owe around roughly 900$ for our phones obviously I know we need to come 100$ out of pocket for rest of the balance. Then when we switch would there be a way we can trade in her iPhone for the new pixel 11 pro xl? Sorry for this being so long lol