Generally, the models will emit different data, and thus the output generated by Windy will differ across models (right now there are crass differences for rainfall on NEMS, ICON, and ECMWF in the area of my interest).
The extent to which models agree probably often is indication of the quality of the (regional) forecast.
Therefore, I'd like to see an ensemble of the available model data - on a map, over time. For a single location, this is comparatively easy to accomplish as demonstrated by https://kachelmannwetter.com/ch/vorhersage/2657896-zuerich/xltrend
For maps - well :)
One idea would be to have multiple IFRAMEs on a single page, keep the synchronized, largely, but have them all render the data of one specific model. Example: I'd be interested in a comparative view of NEMS, ICON, and ECMWF. This could be resolved by having a global time scale for navigation, local read-only time scales on each model for indicating the time of the model, and then showing this all at once?
Also, having an accessible (as in "user-friendly") way to demonstrate that no one model is right could help in educating people?