So, I realized that FeatureLayer.selectFeatures does not adds the default lightblue highlight, you need to set the layer's selection symbol, so I copied the popup's one so that it looks the same :
function setFeatureToDefaultHighlightSymbol(fl){
const type = fl.geometryType;
if(type === 'esriGeometryPoint'){
fl.setSelectionSymbol(this.map.infoWindow.markerSymbol);
}else if(type === 'esriGeometryPolyline'){
fl.setSelectionSymbol(this.map.infoWindow.lineSymbol);
}else{
fl.setSelectionSymbol(this.map.infoWindow.fillSymbol);
}
}
So, I call the above before calling the selectFeatures method, problem is, instead of adding a symbol on top of layer symbol, it substitutes for this one, so it ONLY show the lightblue highlight border.
My question is, how can I have the same behaviour as when I click a feature? My guess is that the Popup adds the selection symbol on the Map graphics layer on top of the clicked feature, but can I do this without having to manage graphics added to another layer?