I finished the game but not sure if I missed out on anything major

**spoiler warning below!!**

So I finished the game and got the good ending complete with post credits scene but I was wondering if I missed out on anything. Immediately after Deeper Well, I directly went to Basil's house and entered Black Space but I seemed to have missed Oasis and did not complete some side quests (ghost party + finding hector).

I was wondering if I missed out on anything major that's part of the "story" aside from achievements? Pls help