I would also recommend against duolingo, whilst it's useful for European languages it's really not set up for East Asian languages at all. The lessons often give little in the way of contextual or grammatical explanations which is really essential for Korean in particular. The best app I've used is Lingodeer although I haven't used it since I started learning Korean around 3 years ago when it was very much in its beginning stages. Even then it was really great, although I'm not certain it's totally free anymore.
As for curriculums, there's 2 main ones I would recommend -
TTMIK and
HowToStudyKorean. You're right that TTMIK can be a little waffly, especially in the podcasts when you're doing relatively easy grammar. Sometimes the explanations can feel excessive, but there are few other curriculums that give proper spoken examples so you can practice pronunciation. HowToStudyKorean has the opposite strength - there's no waffle but it gives all the detail needed. The main issue I have with it is it's very dry and can become boring. It's also very intensive and condensed in a way that isn't very user-friendly and can easily become overwhelming, so don't do a whole chapter in one session because it won't stick. It's pretty much purely grammar with a vocabulary list at the start which is a kind of dull way of learning in my opinion, but it does explain things well. For vocabulary, I'd highly recommend typing out your own Quizlet sets because the process of writing them out really helps. Overall though, if you're genuinely aiming for a high level of ability you'll most likely have to invest in a proper textbook at some point.
As for me, I have 4hrs or more (sometimes 8hrs!) of very interactive classes a day so I don't really use many 'proper' resources other than my textbooks and workbooks. I do use more informal methods for learning outside of classes like movies and TV shows, but I wouldn't recommend those unless you're already at an intermediate level