Here's a post from 2018 on HackerNews with an AMA:

OpenBazaar 2.0, powered by IPFS https://news.ycombinator.com/item?id=16702684

My opinion, ... OB needed a full capability mobile app and it needed a web front-end (to at least search and browse). It also needed something done so that performance using the client (browse, and search) wasn't so terribly slow. OB might have had a window, if it was a couple years earlier, where it might have found a user base (both vendors and consumers) that would have stuck with them while figuring out a solution after on-chain fees spiked.

But once there was the ability to accept bitcoin for payment on Shopify, and also when BTCPay Server came out, there was much less of a reason for vendors to sell on a marketplace like OB.

Vendors want buyers, and OB simply didn't result in any decent volume for the few vendors who tried. Without real vendors, generally the only vendors remaining using OB were doing so because they weren't welcome on eBay and Amazon. So you had a lot of weird stuff, which makes a curious normie get turned off from OB. So the catch-22 (few vendors resulted in few consumers, and few consumers resulted in few vendors) was never resolved.

Even today, there aren't really any bitcoin-related online marketplaces that are finding much traction anywhere.

Following is a copy pasta of the Marketplaces section of an article on my blog. Looks like I need to update that -- some of them are now defunct.