prediction:

• main plot locations are more handcrafted plus quests/factions
• the rest of non-plot locations are just fillers to do gathering and fight procedural generated mobs settlements.
• I don’t think it’s a big galaxy anyway, but probably a couple hundred systems with about 50~70 populated by the developers. So more like “local region”.

did a bit google and I am right on the last bit already. source

There are over 100 Starfield star systems to find and explore, grouped by level that create difficulty tiers depending on where you go at your current level.

edit: oh, and judging from the video shown, their star system’s planets will remain pretty close together just for better visuals. Space is incredibly huge and if they even put planets like what we have the night sky would be pretty boring. They can’t afford to do proper nbodies simulation so most of plantes/moons etc are just orbiting on specific pace/path that are not realistic or physically correct.(judging from how they put planet together, the gas giant vs rocky planet sizes are pretty off as well.)