None of those are in yet.
Tree views and data grids require a data binding API that we have not yet decided on.
HTML view is going to be difficult on Linux as we don’t want to bring in GTK or Qt - but we will get there.
As for the data binding API - sure, this is an extremely important part to architect so it will be both easy/concise and flexible. Yet, IMHO, tree and grid views are vital for practical use. I can't easily imagine an app I could make without these.
As for HTML view - having a full browser widget like Qt WebView would be very cool but it's not a primary necessity. A simple HTML renderer able to display a plain HTML document without user inputs and without JavaScript (just paragraphs, lists, tables and pictures, some basic CSS for text formatting perhaps) would already be extremely useful.