Simon, I did get it to work, I used Update FeatureLayer using applyEdits() | ArcGIS API for JavaScript 4.9. I used sketchviewmodel to draw the features and then do applyEdits()
something like this
var sketchViewModel = new SketchViewModel({
view: view,
layer: featureLayer,
polygonSymbol: polygonSymbol
});
sketchViewModel.on("draw-complete", addGraphic);
sketchViewModel.on("update-complete", modifyGraphic);
function addGraphic(evt) {
var geometry = evt.geometry;
newIncident = new Graphic({
geometry: geometry,
symbol: polygonSymbol,
attributes: {}
});
var edits = {
addFeatures: [newIncident]
};
applyEdits(edits);
}