[David Johnston2]

Ordinary nebulas are too diffuse to hamper starship perception, but there is an exception. Star formation nebulae would would be relatively dense, filled with debris and with a hot centre what would interfere with heat sensors.

Prior to star formation there are dense molecular clouds. If there was interstellar space dwelling life, such things might provide it with "food".

Micrometeorites are the reason why I design even civilian starships with a level of armor.

Rogue planets are very very hard to find. That would make them a good pirate base.

Comets are useful for wilderness foraging for volatiles.

Derelict space craft are going to be an inevitable consequence of interstellar travel and warfare.