I feel like this has probably been mentioned before, but I feel like the key feature that Duolingo lacks in comparison to other language learning sites is the ability to practice conversation. It's all well and good knowing how to translate phrases that can be used in common speech, but I think it'd be useful if each language course had a conversation button where you could have short, scripted discussions with an ai about topics you've recently covered as a way of making sure you can combine grammar, vocabulary and sentence structure to create a correct sentence in response to a random question.
They did this in the apps with chatbots. They were tons of fun and hugely popular but only really worked well for a few sentences. Conversations are so random and varied that the bots were quickly unable to recognize what was being said to them so taht they could respond appropriately.
Also, your post has nothing to do with French so could you please edit it and change the topic to "Duolingo"? That way it won't clutter the French forum and you'll probably get more responses.