The pine-cone connection goes way deeper than just the pineal gland association, though you’re right about that link. The pineal gland is literally named after the pine cone. Descartes called it “the place in which all our thoughts are formed” and it is the biological seat of the third eye.
What makes this relevant to Twin Flames specifically is that the pineal gland is the key to telepathic communication between flames. So even though pine cones aren’t talked about constantly in TF spaces, they carry that implied meaning through the third eye connection. There’s also some fascinating ancient links. The Egyptian Staff of Osiris shows two serpents rising up to meet at a pine cone at the top. That’s basically kundalini imagery - the energy rising from the base of the spine to the third eye. Hindu depictions of Shiva show similar symbolism, with his coiled hair resembling a pine cone interwoven with serpents.