The learning app developer could attract a stampede of bulls soon.Duolingo (DUOL 1.49%) went public during the buying frenzy in hypergrowth stocks in late 2021. That bullish sentiment initially lifted Duolingo's stock, but it lost its luster as its growth cooled off and rising interest rates compressed its valuations.Despite those challenges, Duolingo's stock advanced about 13% over the past 12 months and remains more than 70% above its IPO price. But it still underperformed the S&P 500, which rallied 27% d ...