Dear questioner,
May Allah bless you and increase you in good.
Actions are based upon intention.
A mundane action can become spiritual and otherworldly by the secret behind the person’s heart. This is based upon the famous hadith narrated by sayyidina Umar ibn al-Khattab that the Prophet (Allah bless him & give him peace) said, “Verily actions are by their intentions, and one shall only have that which one intended.” [Bukhari & Muslim]
Also worth mentioning the words of Imam Ibn Ata’illah (Allah have mercy upon him) said, “Actions are lifeless forms whose souls are the secret of sincerity in them.”
Abdullah ibn al-Mubarak said, “How often it is that a small action is made great by its intention, and a great action is made small by its intention.”
So if your friend intends to remind others of Allah through the hijab, then Insha Allah she will be rewarded for that.
Allah knows best.
[Imam] Yama Niazi
Checked and Approved by Shaykh Faraz Rabbani