What is the ruling on depositing a sum of money in exchange for obtaining an agency to sell biscuits, with a monthly commission received on this deposit in the form of goods, and to what extent is that compatible with Islamic Sharia?

It is permissible to distribute goods for a commission; this is an agency for a fee. The agent is trustworthy and is not liable except in cases of transgression or negligence. It is not permissible to stipulate a guarantee from him or for the company to take a security deposit that it uses. Rather, it should be kept by the company as a trust or invested between you on a Mudarabah (definition) basis. If it is highly probable that the company will use it, then it is not permissible to deposit it unless it is invested with your agreement on the basis of legitimate Mudarabah. It is not permissible to take interest on this deposit, as it is usury (riba). Therefore, this agency should not be accepted unless the deposit is cancelled, or the company keeps it without using it, or invests it through Mudarabah.