Regarding Nuwa's mending of the sky, the legends of her past life are quite detailed.
The Five-Colored Divine Stones for mending the sky, the limbs of the great turtle that propped up the heavens.
Moreover, Buzhou Mountain has not collapsed today; compared to the legends of the past, propping up the heavens should be much easier.
After all, in the stories of the past life, the collapse of Buzhou Mountain was highly abrupt and dire, so much so that even a Saint had to act hastily, needing to construct a pillar to support the heavens and mend the sky in a very short time.
But now, there is no need for such urgency; even if four more pillars to support the heavens are refined, it would just be aiding Buzhou Mountain with its task.
After all, Pangu's breath in Buzhou Mountain may be waning, but it has been nourished by the Primordial Celestial Stars Array.