Not self hosted but look at your local library, I am in the US and my library has Mango Languages for free, and Duolingo does not seem to be the recommended way to really learn a new language.
Also faircamp and mirlo.space
Not self hosted but look at your local library, I am in the US and my library has Mango Languages for free, and Duolingo does not seem to be the recommended way to really learn a new language.