@omo_salvadego it's been used to mean "shutting down a project". I've heard it used that way for the first time some 10 years ago when Firefox OS was shut down and it seems to have caught on.
@gabrielesvelto fwiw both were borrowed into corporate speak from other contexts. Pivot came from sports (basketball I think though maybe others) and sunset came from politics where some laws had built in expiry dates.