Just wanted to update my progress. I have gotten the hang of Duolingo and maybe in a few months I will complete the Korean course (unless they add more units).
The most frustrating thing about Duolingo at this point is having to learn topics that I truly have no interest in. Like there was a unit on sports and there will be a unit on the Olympics. I just don't find them as important so I don't care much if I remember those words. So the organisation is just terrible.
It is also quite hard to learn words that you specifically struggle with. I wish there was a feature to mark a word or sentence as weak (this can be done in Memrise) so that it would be repeated to you without you having to get an answer wrong. Although every 50 days, it gives me 3 days of super which has a words practice feature, it doesn't let you choose words to practice. I find some words very similar and would like to have those repeated but can't or at least I don't know of a way.
Grammar wise, I feel like the lessons are not really introducing many new grammar forms. Because I also use Instagram accounts that teach Korean as my source, I pick up on many words and grammars before Duo actually covers it.
If you are using Duo as a main source, I would definitely recommend ignoring the tournaments because proper learning takes time. So take the time to understand each sentence but if you end up focusing on the tournament, you'll be more worried about the speed at which you go through lessons.
The main positive about Duolingo is you form a habit of learning in an attempt to keep your streak.
Finally, I don't think Duolingo can get you to a C1 or even B1 level. A2 might be the best. So you will still need other sources to work with. But hopefully as a high beginner it will be easier to progress and pick up on grammar more easily.
If you don't prefer books, I have seen several wonderful channels teaching Korean and are great if used consistently. They probably introduce the most natural sentences as well because Duolingo sentences aren't so great. Do try to find a channel that suits your need and speed.
And if you are picking up words through kdramas, I found this neat YouTube video that has useful vocabulary.
https://youtu.be/pVqDK8wnONs?si=_5AKdKAQxe4Rvf9I