It is interesting to note that among Buddhist school, the yogic schools, and particularly in the Thai forest tradition, the notion of an Atman ("eternal citta," "pure citta"...) is often encountered. Ajahn Mun, who was, according to the most serious accounts, an arahant and teacher of the devas, spoke of a luminous and primordial citta, beyond all constraints. How can we not see this as the Upanishidic Atman?
Conversely, scholastic Buddhist schools (Buddhaghosa, traditional Theravada, etc.) deny this notion of a supreme citta, but in doing so, are unable to explain the higher states of being experienced by the yogi. Thus, in these schools, it is rare (if not impossible) to encounter an arahant; as Thanissaro Bhikkhu explained, this idea of absolute non-self can be harmful to the practitioner.
Moreover, it is obvious that from an experiential point of view, nothingness can never truly be realized (neither release if it were pure nothingness), so the yogi who has traversed all the higher states always has a positive experience in every aspect, and can only describe it in positive terms (luminous, spacious, boundless etc...) or eliminate misconceptions about it.

See :
https://www.forestdhammatalks.org/en/ajahn_martin/dhamma/Ajahn%20Martin_Is%20the%20citta%20atman%20or%20anatta.pdf