I don't think displaying interpolated NWP forecasts on Windy maps would be a good idea...
Interpolating satellite images is performed for high frequency (10-15 minutes) observed values. There are small chances to get wrong results in practice: at such an image resolution and frequency, weather changes are small. Here, relatively simple mathematical tools are enough.
Interpolating forecast values computed for every 1h (or 3h for users who don't pay :o))), is really tricky in practice and should be only performed by forecast providers. Values are already computed with some error; interpolating them would get even bigger errors. Here, just mathematics is not enough. In 1 or 3 hours, weather changes a lot, thus using purely mathematical interpolation risk is to get nice animation from an artistic pov., but completely wrong from weather pov.