[dfox]

NAND flash isn't random access even for reading, but generally these limitations are not inherent in the technology, but are motivated by reducing the die area per bit of storage (and thus cost). Purely random access "Flash" is typically called EEPROM and readily available with SRAM-compatible interface (and costs several times more than SRAM).

In the microcontroller space there is for example TI's MSP430FR series which has unified non-volatile storage based on what could be described as core-memory on chip.