Another way to do this would be to set the srcDoc property of the html.Iframe component with the output of the plotly.offline.plot call. Note that graphs created this way won’t be able to be the callback Inputs the way that the dcc.Graph is able to be (Part 3. Interactive Graphing and Crossfiltering | Dash for Python Documentation | Plotly).
For more on srcDoc property, see Folium maps and Dash - #2 by chriddyp.
I’d still like for Dash to support this “the right way” as described in the comments I made above (e.g. Animations in Dash - #2 by chriddyp)