How can I get ALL features from a GeoJson source in mapbox?

Question

I have a source layer like

{"
  type:"geojson",
  data:"http://www.example.com/markers.geojson"
}

Now, I need to make some calculations on the features. But since the data is a geojson URL, I don't have direct access to it. I might load it aside but it make things more complex.

I know you can get source features using querySourceFeatures, but this only gets features within the viewport bounding box :

The domain of the query includes all currently-loaded vector tiles and GeoJSON source tiles: this function does not check tiles outside the currently visible viewport.

This seems to be a recurrent question, but hell! Is there a solution that works to get all the features of a source ? Looks like an obvious thing to have.

Thanks a lot.