The latest feature to make it's way onto mainnet is private market/private store creation allowing any user to create a private store or a private market. with a private store you can invite others to sell and create a marketplace of your own or you can open a private store for your customers to access you products.
oh and the marketplace and creation of private markets and stores is completely free! only the listings of products incurs a fee and the fee is very low(1-2c per day per listing)
https://particl.news/new-development-roadmap-released-b7b745b18309
For a recap on 2019 development > https://particl.news/particls-open-marketplace-progress-so-far-cfaa29d1de02