The ones I’m using now are specific to Japanese (WaniKani and Bunpro), but if you want to level up from Duolingo I would recommend Memrise for a similar bit more effective experience. They have a Portuguese course.
If I were in your shoes, I would do Memrise to fill the little moments throughout the day. But the focus of my studies would be (1) a local community college Portuguese course; (2) the FSI Basic Portuguese course (or another drill heavy course from the 60’s, maybe linguaphone?) for self-study drill practice, 30min a day; and (3) a good sentence deck in Anki, minimum 10 new cards per day.
Idk, I started out using both Memrise and Duolingo in August 2018 for French, used both for a couple of years but now use Duolingo only for French and Italian the last couple of years. I think both are good but prefer Duolingo. But to get conversational I believe you would have to go to more personal methods…
There’s no app that can build up conversational fluency. You can’t master a thing without actually doing the thing.
SRS apps can be good for building up a vocabulary base. Self-study drill based programs like the old FSI series can be great for internalizing grammar rules so that you don’t have to consciously think about it.
That does give you a great foundation for developing linguistic fluency though, should you relocate to the country or start immersing yourself in native media.
If I were in your shoes, I would do Memrise to fill the little moments throughout the day. But the focus of my studies would be (1) a local community college Portuguese course; (2) the FSI Basic Portuguese course (or another drill heavy course from the 60’s, maybe linguaphone?) for self-study drill practice, 30min a day; and (3) a good sentence deck in Anki, minimum 10 new cards per day.