What I find most worthwhile in study Kanji beyond WaniKani would be Joyo Kanji (173) and extraction from WaniKani context sentences (211). So the total good to be studied would be 173+211 = 384 = about 10 levels.
WaniKani context sentence creator like to create sentence with many Kanji, much more than Core 10k context sentences.
I find non-Joyo N1 kanji to be less useful, though. So, in my levels, I went from level 61->70, 78->80, 76, 71->75, 77, sequentially.
The such useful WaniKani context sentence Kanji list by frequency would be (non-Joyo, non-WaniKani)
In the wild, I still see Kanji more than these, but these should cover most that the author wouldn’t add Furigana.
Yeah, WaniKani context sentence creator didn’t include Furigana either.
About how to study Kanji outside WaniKani, I suggested my learning pattern here. In short, always learn associated vocab well before learning individual Kanji. (This is a little in contrast with WaniKani itself that teaches Kanji before vocab.)