LÖVE

How to read data NOT from AppData (on Windows) and NOT from .local / share / love (on Linux), but from ordinary user memory (from an SD card, for example)?

You can't without using a library or ffi. Unless you are on Android. I believe the flag "t.external" or whatever it is is still a thing. It basically determines where your save directory is located. The Android external fs or the internal one. You still locked to just the save directory though.

Do you know if the developers plan to add this to LOVE?

I am pretty certain the answer is no. I forgot the reason why tbh. I think its mainly to prevent user error. Honestly thinking about it it is a pretty stupid limitation. Although I will say in the scope of strictly game development it's reasonable. I don't really play games that often but I don't see needing access to the full filesystem as useful for most games.

I believe you can freely use the io.xxxx functions, if that helps.

I need it, becuase I try to make game engine. I fought good analog - callback function "love.filedropped"