When searching for a business to buy, make sure you do your due diligence. There's a lot of junk out there and many "brokers" just make up their numbers/claimed legitimacy to win business. Once you've got past that, you then need to do due diligence on the business itself.
Passive businesses are not impossible to find, but it does depend on your definition. You can't buy any business and do absolutely nothing (truly "passive"). Even something low maintenance will require 1 hour a week, especially if you want it to last for years. Expect to pay a premium for businesses like this but be very cautious around claims from a seller. Number of hours worked is the easiest to misrepresent (and the hardest to prove). Almost every seller claims to work "2 hours a day" but IRL I've never met a business owner who works less than 10 a day :)
To answer your question directly, don't just look at marketplaces, check out brokers and advisors too. If you're upfront with what you're looking for and budget, most will send you options that are a good fit.
Good luck with your search!