try to unplug → replug
and redo
adb devices
look like you won’t be able to run ADB commands because device was not prior enabled from
→ android settings → system → Developer Options → USB debugging
installing TWRP, and booting on it will automatically enable MTP files transfert,
you should at best copy you internal_storage content (if not encrypted) using your PC file-manager.
at least, (after mounting /system), using TWRP “advanced file-manager” you will be able to freeing some space by deleting some apps in /system or in /data
and perhaps boot to regular /e/OS
what OSes can you run on you PC ?