Turns out the Pico uses a 16MB chip with a smaller area than we have been using. Easy way to save space since that flash IC is one of the biggest things on the board right now.
https://www.digikey.com/en/products/detail/winbond-electronics/W25Q16JVUXIQ-TR/15182017?s=N4IgTCBcDaIOpgKwEUCMA2AUgNQKoA0BJZEAXQF8g