This may give you some ideas, although my floor plans are in 3D not plan view. It's changed quite a bit since this post to include more devices. This kind of dashboard is custom created using html/css/javascript.
You can certainly use an image as a background to a standard Hubitat dashboard and then position tiles over the top to achieve a simpler version. But it's quite fiddly to set up with a very high column and row count so that you can finess the tile positioning.
