Any way to change my final goal? (Spoilers)
Solution 1:
No man's sky will remain an open sandbox. no matter what choices you choose throughout the story. You can select new missions, ignore them and build bases, ignore that and just fly the stars, whatever.
The only thing these choices alter is dialog and maybe a handful of events after the choice, but never any lasting or drastic changes. Your galaxy map will always have the navigations for Center of your current Galaxy, current mission(if any are active), a black hole, an Atlas Station, or just free explore. You can do whatever you want, whenever you want.