Don't you wonder why there's only two ootsutsuki that came to attack?, instead of the whole army that Kaguya was talking about?, its because Sasuke's arm fought against the renaming enemies and won, his arm was never destroyed, once he clashed with Naruto, his arm did get removed, but he teleported his arm to another dimension and was gonna re-teleport it to the battlefield to kill Naruto but could not because he couldn't locate his arm in the other dimension's, due to his inexperience with the rinnegan, it makes sense that Sasuke teleported his arm, because when you think about it, when did Sasuke ever pass out when he clashed against Naruto?, the reason he passed out wasn't because of the clash, it was because he used his remaining chakra for the teleportation.
Years passed Sasuke trained throughout the years, his lost arm also got stronger aswell, it then ran into beyond kaguya army at one point and reacted on his own due to Sasuke's mass power, and defeated most of the army, but momoi and kinishki was not with the army and was at another place at the time, and Sasuke still does not know of this because he still could never find his arm
This is my theory
The End.
Years passed Sasuke trained throughout the years, his lost arm also got stronger aswell, it then ran into beyond kaguya army at one point and reacted on his own due to Sasuke's mass power, and defeated most of the army, but momoi and kinishki was not with the army and was at another place at the time, and Sasuke still does not know of this because he still could never find his arm
This is my theory
The End.