This is the Lightning web component app for the LWC badge in the Salesforce Trailhead training certificate. 

Salesforce created a demo exercise for their certification with some generated data and code to get you started, and you basically create an app showing various boats you can filter through and see details for, and also have a map pin update on a map on the sidebar of the page.

For this badge, Salesforce does not allow sharing of solutions, in any way. In fact I was required to basically sign an NDA (in the form of a checkbox) saying I would not show my code. Here is a quick preview (I showcased the codebase in such a way that I am pretty sure nobody could backtrack any meaningful answers to help them with this challenge) of the codebase and one example component, which shows how the components are structure. The HTML has a templating language which can use exposed data from the .js files. The javascript file shows the object oriented style of lightning web components, and some LWC specific decorators - @wire and @api. The framework has a data flow system called "messages" to communicate data across DOM elements (or it can simply share it with child or parent elements) to create reactivity.