In the game files, the endings are 'Endgame_FEMALE_A.bk2' and 'Endgame_FEMALE_B.bk2' and of course, a male counterpart for each. If you want to do side-quests for all four factions, then you’ll need to do them before you conclude the main story. The only impact is the state the world is in afterwards and who you can and can’t do questions for. All roads lead to one cutscene, which only varies slightly.
