ValveIndex or Hololens 2

Gift for my brother, thoughts on which would be bests as I'm aware Hololens 2 lacks Software but idk much about the Index and seems to be jst for games and not well optimized for development? He's a engineering and idk if either would be useful for him.

Edit: after a bit of research I purchased the hololens 2, even though it's a bit more expensive and lacks a few good feature compared to the index. Will be purchasing the index next time as these will be his graduation gift. I appreciate the help.