I'm trying to build a msd with stm32f4 which will be connected to a pc with USB. I need to visualize it as "USB drive" formatted in FAT. Initially I was planning to use a nand flash but I can't use it "bare bone", I need a translation layer, can someone please link application notes/articles about it? now that i know what I need I will also search myself!
Initially I was planning to use a nand flash to read and write data, but I can't format it in FAT.
Sure you can -- if you use a flash translation layer. That's how SSDs and USB flash drives work, after all.
That being said, an SPI or QSPI flash device will probably be easier to get started with.