Will God hold a person accountable for sins committed out of ignorance, due to not having received advice or not having sought to gain understanding in matters of their religion?

Excuse due to ignorance is not absolute. Rather, sin is incurred by negligence in seeking knowledge. And even if the ignorant person is excused in some rulings, such as not being declared an unbeliever (kafir) or not having to repeat worship, there must be some form of accountability if there was negligence. Umar ibn al-Khattab, may Allah be pleased with him, lashed an ignorant woman who committed fornication one hundred lashes and exiled her, as a disciplinary measure for her negligence in learning, but he did not apply the hadd punishment to her because she did not know the unlawfulness of her action. Ibn al-Qayyim divided the people of innovation (Ahl al-Bid'ah) into categories: among them is the ignorant follower who is neither declared an unbeliever nor a transgressor if he is unable to learn guidance, and among them is the one capable of seeking and knowing knowledge, but he neglects that out of carelessness. This person deserves the threat (of punishment) and is sinful due to his negligence.