First, please do not start singing that song in chat. So we have a new Trade Shop plugin that integrates directly with LWC! But what does this mean for you? Using this plugin, and the handy trade center built right off the main survival world portal, you will effectively be able to sell and buy items whilst you are offline.
If you want to find out how to use this plugin, please see the instructional signs in the trade center, or see the official plugin pages here: