So as far as I'm understanding it, there are two ways to find things to do in unexplored space.
One is to look for these white diamonds, which are some kind of event going on in orbit of the planet.
The other is to look for this symbol, which represents the presence of a settlement.
Is that it? I'm seeing the "..." marks on some planets, but the content there seems to be near-universally pretty bad - usually just some pirate outpost or warehouse with no real story or quest or dialogue, just a trash mob of enemies and some crap loot. I've also tried landing on procgen planets and exploring their caves and such, but again the content is simply not worth bothering with for someone who isn't interested in the resource gathering and outpost building aspects.