Is it possible to access Level Blueprint functions/variables from other Blueprints?

Yes/no/how?

LevelScriptActor instance can be only accessed in C++ as far as i know

Yes. Create a blueprint interface and add it to the relevant blueprints using the blueprint props button, including the level blueprint.

Level BLueprint doesnt have “Add interface” in its blueprint props.

Ofcorse you can do other way around, accessing other objects from level blueprint and considering there no way to access level blueprint object in other blueprint it’s recomanded way to do things. Alternatively you could also send level blueprint refrence to other blueprint using “Self” node

ok i consider this as an answer