I suppose it really depends on how you see light/heavy and what you consider "diaspora writings" or "LGBT themes", whether you refer to text or subtext. For example, Han Kang writes a lot about alienation which is a thing that people in diasporas do experience but people experience it in many other contexts. When looking at her texts on the surface, most of her books are set in Korea and are about very Korean things, e.g. Jeju Massacre, Gwangju Uprising, etc.