These little chips are like miniature SSD drives for your electronics. When you don't need something with as much storage as a micro SD card, but an EEPROM is too small, SPI (or QSPI) Flash chips give you on-the-order-of megabytes, with little cost and complexity. We use these chips all the time on our CircuitPython boards to let folks store code and assets like animations, fonts, images, configurations, audio clips, etc! A great way to add datalogging storage as well.
This chip has 2 MByte of non-volatile storage (16 mega-bits) and is well supported by CircuitPython and also our Arduino SPI Flash library. The standard SOIC size is fairly easy to solder, and it has the standard FLASH chip pinout so its good for just about any FLASH use including FPGAs or flash-less microcontrollers
You can also solder it onto the back of your QT Py board to add flash - note the QT Py will no longer be easily surface mounted as there'll be a lump on the bottom. You will need the customised CircuitPython build so it knows to look for the flash chip!
The Teensy 4.1 also can use an external FLASH chip there're pads on the bottom