As the OP mentioned, seems inefficient to upload RAWs for processing and culling online. However, extracting and uploading the embedded or sidecar full-res JPEG

As the OP mentioned, seems inefficient to upload RAWs for processing and culling online. However, extracting and uploading the embedded or sidecar full-res JPEG, editing that non-destructively, then applying the edits to the offline RAW copy seems like it might work better.