As a first-century woman in Judea, it seems unlikely that Sapphira would have had much legal say in whether property is sold and how much it's sold for. Yet Peter says that she and Ananias both agreed to deceive the Holy Spirit. Under what circumstances would a first-century Jewish wife have had influence over property decisions?
The independent capabilities and trustworthiness and sheer domestic competence of women is borne out by the Hebrew scripture, as in Proverbs 31: 10-15 -
Who can find a virtuous woman? for her price is far above rubies. The heart of her husband doth safely trust in her, so that he shall have no need of spoil. She will do him good and not evil all the days of her life. She seeketh wool, and flax, and worketh willingly with her hands. She is like the merchants' ships; she bringeth her food from afar. She riseth also while it is yet night, and giveth meat to her household, and a portion to her maidens.
And, more notably and even more pertinently in verse 16 :
She considereth a field, and buyeth it: with the fruit of her hands she planteth a vineyard.
Sadly, Sapphira conspired with her husband and misused the above skills for evil deceit, rather than for honest charity.
But there is no question that women had considerable autonomy in Israel.
Nor is your doubt of Peter's competence and authority supported by the facts. For if Peter was in error, why did first one, and then the other party fall down dead as Peter uttered the very words which precipitated their judgment ?
Divine and/or angelic power was exerted as the words left Peter's mouth.