Spoilers, I guess, in case anyone who hasn't played is reading this
Areas that I still need to investigate:
-I landed on the Quantum Moon, but I can't get to the North Pole without leaving the atmosphere and resetting my position. I also found a tower there to move the moon, but I wasn't able to leave the tower after going to the "sixth location"
-The Tower of Quantum Knowledge and the Tower Shard-- I have a feeling the two are linked and the Tower Shard is key to getting in...but I haven't figured out how that would work yet.
-Still haven't found a way to get to the Black Hole Forge, which is also on Brittle Hollow
-I'm missing something in The Vessel. I suspect I'm supposed to enter the coordinate symbols I found somewhere else but I wasn't able to access my screenshot at the time.
-I was able to change where power was going in the High Energy Lab on Ember Twin, but I have no idea what actually changed when I did that.
-I still haven't found anything of note about Hollow's Lantern, which feels a bit strange given it has space on the map.