The SlavoLingo project includes 17 complete A1 courses for LibreLingo of the following languages: Interslavic, Belarusian, Church Slavonic, Czech, Kashubian, Old Church Slavonic, Lower Sorbian, Croatian, Upper Sorbian, Polish, Rusyn, Russian, Slovak, Slovenian, Serbian, Silesian, and Ukrainian.
In case you want to modify the courses, feel free to do that and compile them with the python script afterwards. But in case you don't want to compile them or only need one of the courses for LibreLingo, go into this repo.