The upcoming version of Terminal-BASIC uses SPIFFS to implement NVRAM and file system commands on esp8266:
I'v test it on ESPBoy device. There is no suuport of TFT screen, buttons, sound and LED for now, but the port is fully functional, using UART.
Sketch with data folder for SPIFFS, containing some BASIC programs: terminal-basic-2.3-a1
DIRECTORY command shows the files list. Unfortunately, the files, written using esp8266 SPIFFS uploader have names, starting with '/'. To start AMAZING maaze generator, for example, one needs to type the command
DLOAD "/AMAZIN" without BAS file extension