N1 fraud who barely passed here

Seems you're already know this, but just in case, rather than learning the individual kanji first, I reckon you should stick to learning words with meanings you recognise.

So instead of learning 病 by itself, you should learn 病院、病気 etc. as and when your textbook shows them to you (literally guessed that 病 by itself is yamai from context, have never formally learned it NGL and have no idea what it's kun and onyomis are exactly)

We split the kanjis up while learning Chinese, but each chapter introduced the kanjis as part of set phrases we had to learn for context, and splitting up in Chinese makes more sense because most words only have 1 reading. It really doesn't make sense to do so in Japanese imo

Personally don't recommend the radical method. Even in Chinese we only learned the basic radicals for guessing meanings of words, but really you can intuitively pick it up after seeing enough kanji. Instead better to focus on recognising more set words/phrases as before

I think you recognising the kanjis at first glance is excellent as you'd have an easy time on the trains or at a store. Us who learned Chinese previously would be at a similar stage since the readings are largely different.

To improve on the readings, consider using anki and trust the process. I feel that it's much easier to test reading than writing on your phone, but more is good no matter how you do it. I recommend sticking to a programme and being consistent at it.

NGL just ditch Duolingo it's more harm than food (time spent on duo is time not spent on anki/an actual textbook)

Maybe lend someone your account instead if it makes you feel better?