Marketplaces
These are the places where you can expose your info products for the buyers. Or you can buy some stuff that can be use in your own products you are developing.
These places are a meeting points between producers and consumers. Usually are offering support for publishing the products, marketing the products, buy/pay for the products. All of this for a small fee.
Are you an backend expert but you don't have experience in frontend development. You can buy a theme from themeforest.com or you can use from free some UI components from codepen.io.
Are you an expert in UI or UX but the backend development is not your forte point. You can use an REST api from rapidapi.com.