1. Add new Browser element
2. Use url: https://www.twitch.tv/popout/<your-channel-name>/chat
3. Choose a good width and height. mine (400,400)
4. Use this CSS to hide all elements that are not needed

1body { background-color: rgba(0, 0, 0, 0.2) !important; overflow: hidden; }
2.chat-room { background: transparent !important; }
3.tw-root--theme-dark .chat-room { background: transparent !important; }
4.consent-banner, .chat-input, .stream-chat-header,.tw-transition,.chat-line__status {display: none !important;}

Where rgba(0,0,0,0.2) is the background the 0.2 is the alpha value 0 transparent 1 opaque