Well it doesn't support QSPI, and the SPI implementation doesn't map into the memory space of the MCU directly.
You could use SPI to connection to W25Q256 or MT25L256 type devices in 8 or 16-pin packages. These are NOR Flash.
The F429 can support F(S)MC peripheral for parallel RAM or FLASH, but these soak up a lot of pins vs SPI, QSPI type devices.
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