Several Federal Reserve banks run public GDP nowcasts that update automatically every time a component data point lands, and they routinely disagree with each other by a full percentage point because they weight the inputs differently. Their historical accuracy is measurable. You blend them by past performance rather than treating whichever one got quoted in the press as the truth, and trade growth and recession markets against the blended estimate.
Markets on Polymarket where gdp nowcast tracker blend is the natural play: