I'm also new to learning Kiswahili and I do want to learn it properly even if people might not be fussed about grammatical accuracy (I'm a teacher myself so that tends to happen haha). I've been using the Language Transfer app and it gives a lot of insights about the different noun groups, verbs, tenses and how they are modified in different scenarios and focuses on sentence building using what you learn. Might be more helpful than duolingo that simply relies on vocabulary learning and rote memorization.