I created a similar simple client. My goal was to make something as simple as possible that just shows one person's posts. https://jgettbtc.github.io/simple-nostr-client/

it's definitely something when you refresh the page and the posts roll in from the websocket. Like drinking from a firehose!

This is entirely in Javascript and loads from the browser from a local file? Or does this file need to be loaded from a central server?

Very impressive!