The same in my country. Because of how convenient online shopping has been, there are a lot of products to get affiliated with. Just register on the online shopping that's very popular in our country, we've got 2 so far and just promoting the link alone on social media will be fine and you'll get the commission once the sales are successful. It's not costly but you'll have to make the marketing very convincing and it's up to you on how you'll make those promotional videos. So, you're right that marketing is the key to it and it's passive income once you're able to establish those links, promotional videos, articles and any other marketing materials.
Given today's technological developments, shopping for anything can be done online. Although there may be some products that cannot be purchased online due to the dark side, such as fraud. However, what is clear is that many people are taking advantage of this development by selling their products online, and those who are successful can be said to be because this online business is real, not just empty talk. We know that nowadays there are a lot of advertisements being marketed, one of which is through cell phones. Almost all cell phone companies provide attractive advertisements because the goal is to attract a lot of people. So, this attractive marketing has a significant impact, in my opinion.