The owner of a marketplace, unlike the owner of an online store, does not sell anything, because he only provides space for someone else’s business, provides traffic and marketing support, receiving a commission on sales. I like this type of business very much and have more than once thought about opening something like this. Each marketplace is based on one of the three basic models, namely c2c, b2c, b2b. I personally would open a C2C with https://www.codica.com/blog/build-c2c-marketplace/ where both parties are individuals who interact with each other as equals.