Used to be able to upload non-binary files from “data” folder to FLASH via SPIFFS. For example: “index.html”. Changed to LittleFS libs and includes after found out SPIFFS is going away. Now can’t upload any non-binary files in IDE version 2.0. Tried going back to SPIFFS to no avail. Also went back to old IDE version 1.8.19 and tried. Still missing “ESP8266 LittleFS (or SPIFFS) Data Upload” under “Tools” menu. One last thing. Noticed FLASH file size selection menu “Tools>Flash Size” now says “OTA” instead of “SPIFFS”. Do not want to use OTA to upload binary files to FLASH.
Uploading non-binary files to SPIFFS is working again. Did a complete uninstall of both Arduino IDE versions 1.8.19 and 2.0. Searched for and deleted all “hidden” Arduino files and directories. Then installed version 1.8.19 (*.exe) only. Lastly, carefully followed steps in https://randomnerdtutorials.com/esp8266-web-server-spiffs-nodemcu/.