The Raspberry Pi Pico comes with 2 MByte FLASH. If more is needed for example to store data or for a data logger, this article shows how it can be extended with a 16 MByte serial flash using the LittleFS file system.
Raspberry Pi Pico (c-sdk)] Storage: Ep2. Multi external flash
W25Q32 W25Q64 W25Q128 Large Capacity FLASH Storage Module SPI
Raspberry Pi, Page 239
Raspberry Pi Pico (c-sdk)] Storage: Ep 4. TinyUSB USB Mass Storage
SPI FLASH Breakout - Flash memory module W25Q128 - 128Mb / 16MB
RP2040 Microcontroller Camera Development Board, Onboard HM01B0
Erich Styger, MCU on Eclipse
For Gamecube SD2SP2 SD Card Adapter+Raspberry Pi Pico Board
BLE with WiFi and FreeRTOS on Raspberry Pi Pico-W
GitHub - NegasonicX/Raspberry-PICO2040-Flash-Storage: The
Raspberry Pi, Page 239
FLASH MCU on Eclipse
Raspberry Pi Pico – Micro SD Card – Photo Frame -– 3.5 Inch
Expand Your Raspberry Pi Pico's Memory by Adding a microSD
