No, not correct at all. Seems there are at least a couple wrong assumptions in this question.
The default startup code only initializes FlexSPI2 if it finds 1 or 2 PSRAM chips. To access anything else, you need to configure FlexSPI2. For flash chips, that config is normally done by LittleFS_QSPIFlash or LittleFS_QPINAND.
If you want to access anything other than PSRAM, and you don't want to use LittleFS, you have to initialize FlexSPI2. You can grab code from LittleFS or other older code, but you really need to understand none of this is done automatically. You have to do it. You must program the FlexSPI LUTs to perform the specific action needed to access the flash chip.
But no matter what you do, flash chips are NEVER directly writable as if they were normal memory, like you get with PSRAM. You can only read flash chips with memory mapped access. All writes have to be done using the FlexSPI IP CMD interface.
If you're going to use memory mapped access, don't forget about the MPU. Today the default setting is very permissive for FlexSPI2, but it may someday change to be automatically restrict memory mapped access to only the detected PSRAM chip(s). If you will access memory, best to explicitly configure the MPU to allow the range you will actually use.
