These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Beam Spam: Depending on your definition of "spam", some enemies may or may not do this, as may the players themselves. The Devolariums are particularly notable for large amounts of visual firepower. However, the visual attacks make no difference to the damage received.
Also, the Rapid Salvo Battery supposedly does this in-universe, especially judging by its SFX, although in gameplay its actual effect is to change the colour of your Frickin' Laser Beams and massively increase your damage.
Space Fighter: The player's ship seems to be one, although the scale is unclear. Is the Goliath the size of a house, a skyscraper, or a city? The Phoenix seems to be only big enough for the pilot, a laser weapon, an engine, and some other assorted hardware, which would put it at the size of a (large) car. Based on the scale between it and the Goliath, as well as the size of the Goliath's (possible) cockpit, the Goliath would be somewhat larger than a (large) house.
But then, since when have games like this ever had sensible scaling?
Unobtainium - most resources in the game could be considered this.