From what I can tell there is at least ONE run of All Trophies/Achievements for almost all the mainline games....except for this one.

So I have to ask, how long would an all trophies/achievements run realistically take? I know multiple saves for the endings would be a must and that the game is pretty grind heavy. My guess is around 10 possibly 12 hours considering that the runs for RB3 and VII were around 10 hours.

Reason for no Re;birth 2 all trophies/achievements runs yet is due mainly to 1 trophy. The Stella dungeon master iirc. That alone makes this run go into the possibly close to or way over a days worth of time even in speedrun form.

Gotcha. I think in that case an almost all trophies run might be more doable. Think of it as like 98%.

Yeah your 10 hour estimate seems reasonably valid. I think if we ignore Stella's existence entirely then this one is less grindy than RB3/VII but maybe a little more grindy than RB1.