I think it's settled
That is the voice of an old mature woman
I mean it was kinds obvious since this thing wears a long dress and a head veil, plus the feminine thematic in her flower room
I wished for a man to avoid another Kaguya ( Old woman + creator of said world + final villain ) also got one more similarity but it's not anime yet.
If i remember Toei did a thing of their own rushing Oden before he was revealed in the manga thanks to the ever small gap between them
They rushed him and he was nothing similar when revealed, so maybe this is another case. I still got small hope since .... gotta wait for that to be said in the anime.