ugh.. will have to put this aside for awhile. seems so close and still so outta reach! 🗺️ feels like i must be making a novice mistake since passing in the coordinates works

I was definitely going about it incorrectly. All I had to do was ask the server to respond in the projection I wanted:

layer_details = arcgisRestFeatureLayer.queryFeatures({
  url: '<https://corsproxy.io/?>' + encodeURIComponent('<https://services9.arcgis.com/weJ1QsnbMYJlCHdG/ArcGIS/rest/services/>' + "Country_Polygons" + '/FeatureServer/0'),
  outSR: '4326', // WGS 1984
});