You can trade on the market, but you can't pay natively. They have what they call a multi-wallet:

https://openbazaar.org/blog/openbazaar-2.3-release-with-multiwallet/

With the 2.3 release OpenBazaar users are no longer forced to use a single cryptocurrency, but can buy, sell, send and receive multiple coins with the same wallet.

At the time of release there are four supported cryptocurrencies: Bitcoin, Bitcoin Cash, Litecoin and Zcash. Ethereum support is nearing completion and will be added soon, and other coins will be added later.