I do not want to host downloadable files on server
One option is to host the files remotely but download them on-the-fly (in a callback) or on app start. Here’s an example:
df = pd.read_csv('https://raw.githubusercontent.com/plotly/datasets/master/2011_february_aa_flight_paths.csv')
The other option would be to write your own Dash component that would download the file client side. We have a tutorial on writing Dash plugins here: https://plot.ly/dash/plugins and a tutorial on React here: https://dash.plot.ly/react-for-python-developers. Companies can also sponsor open source Dash components.