This is not just a throwaway comment, either. I've built and run a language school for four years (with two partners), taught thousands of children, worked at a language learning startup, and have read a lot L2 acquisition papers and know this space pretty well. I also contributed to Anki long ago, but I'm not a huge fan of using SRS for learning vocabulary. Extensive reading (and listening once you can) is a far better strategy. (Anki is pretty good for memorizing discrete pieces info though, such as how to write each Chinese character or all the atomic weights and numbers on the periodic table).
As for engagement, I think Duolingo is pretty boring compared to making new friends, talking with people or even just reading a book about something I'm curious about. If you're learning any popular language (e.g. English, French, Spanish, Mandarin, Japanese, etc), you'll be able to find some pretty good graded readers aimed at beginners that let you start actually reading in your first few months of studying.