The most generic solution to this is going to be per-component loading states, as discussed in 📣 Dash Loading States. This is a big project, and we’re looking for companies or organizations to help sponsor the work (Consulting, Training & Open-Source Development).
Another alternative is to build your own component (Build Your Own Components | Dash for Python Documentation | Plotly) that provides properties / attributes that represent the different stages of this component (“loading”, “done_loading”, etc).