Before Hagoromo buff Sasuke chakra was average and never stated to be nowhere near bijuu level. He was exausted against Gaara,Deidara,Itachi and Danzo fight which proves my point.Tf? It's common knowledge everyone's chakra grows and get stronger till their prime. VOTE 2 Sasuke wouldn't have been able to open so many portal's to her dimension spam ameno and Susano'o while not being 100% on chakra. How about you try and prove me wrong.
And you cant simply go from average chakra to bijuu level chakra. You have to show signs of large reserves from beginning.
You can make progres but not on that level.
Opening portals was something Obito and Sakura could do and Momoshiki too. Kaguya dont open portals she summons another dimension (and open portals too but her Amenominaka is sumoning whole dimension)