Since women could not be circumcised, how were they saved under the old covenant in Galatians and Acts?

It is because in those days the man was the essential, counted member of the household. When a census was taken, only the men were numbered; when soldiers went to war, only the men were sent; every reckoning was based on the man as head of the household with one vote per family. When Israel came out of Egypt, Numbers counts only the men, over six hundred thousand, with no separate counting of women and children; likewise when Jesus fed the five thousand or the four thousand, only the men were numbered. So whatever the man belonged to counted as Israelite: his wife, his daughters, and his sons were all Israelites and all among the people of God. The daughters were not excluded because they could not be circumcised; they were automatically citizens of Israel and of God's people, though there were certain rituals in Exodus and Leviticus that applied when a daughter was born. Circumcision never saved anyone; it was simply the requirement a man had to fulfill to remain in Israel, and refusing it would put him outside the covenant people. So the woman was saved as a member of God's people through the covenant household, not through circumcision.