I stumbled over this python gem https://streamlit.io/ and was wondering if using that over PyCall is a good idea given that a lot of data transfer will happen. Are there good alternatives for it in Julia?
Yes - Pluto.jl !
It is a very different approach, but great for making interactive dashboards, etc., as well as for interactive public websites (see Introduction to Computational Thinking).
I think Pluto.jl also wants to add a dashboard mode, which lets you reorganize all the input and output regions.