Is a woman’s good deeds, such as prayer, fasting, and supererogatory acts, rendered worthless if she wears her hijab in front of people out of pretense and to avoid blame, knowing that she might abandon it if she finds acceptance, and is it better for her to maintain the hijab to avoid blame or to abandon it entirely until she wears it sincerely for the sake of Allah?

The hijab (definition) is an obligation and a شعار (symbol/emblem) for Muslim women, embodying their modesty and chastity. A Muslim woman must adhere to the legitimate hijab with its conditions, wearing it seeking the countenance of Allah, not for ostentation (riya').

A woman who wore the hijab out of ostentation is not required to remove it; rather, she should continue wearing it, correct her intention, and avoid ostentation.

Ostentation (riya') is a sin related to the act it permeates; it does not invalidate other deeds like prayers and fasting, nor does it invalidate all deeds except for major shirk (definition) (polytheism).