Load geoJSON source from file

Hi

I have a fairly large (20MB) geoJSON dataset that I want to add as a source. Reading the file from disk, then parsing and adding it does work, but it's really rather slow:

        const routesFile = nodecyclerData.getFile(`routes.json`);
        let routesText = await routesFile.readText();
        let routes = JSON.parse(routesText);

        await this.mapView.addSource(`routes`, {
          'type': 'geojson',
          'data': routes,
        })

The docs mention a way to skip all the extra parsing: https://docs.mapbox.com/help/troubleshooting/working-with-large-geojson-data/#store-geojson-at-url. As far as I could test, this method does not seem to work for ui-mapbox. Moreover, it would require the device to go online.
Does anyone know how to deal with this?

Start at the mapView.addSource call and review ui-mapbox's source-handling entry points, using the local-file flow through getFile and readText as the reproduction. Compare this with the linked Mapbox large-GeoJSON guidance; done means a local 20MB GeoJSON source can be added without requiring network access or manual JSON parsing.