Is it permissible to take money in exchange for promoting a company's product, knowing that I did not request it, and the transaction will be directly between the buyer and the company, without my involvement in the deal?

If the promotion of goods is outside official working hours, then there is no harm in it. However, if it is during official working hours, it is stipulated that permission must be obtained from the company, because the employee's benefits during working hours belong to the company.