I don't define it that way and I never will.
The concept of what "end-game" means is pretty established, and has been for decades now.

Its content you do while at max level that progresses your character.

If it doesnt progress your character in some way, its not an end-game task.

If it can be done before end game, its likely not an end-game task; though more and more games are doing time-locked tradeskilling that you can do at lower levels but only benefit you at max level, because time-locked means fun! or something silly.