Wanikani is just not useful enough, but could be

[Vanilla]

Googling both with lead you to finding them as the very first result

Houhou SRS

Core 10k non-WK sort by frequency [Spreadsheet]

It was Advanced words with easy kanji (a list) by Leebo gave me the idea. Also, top 15000 words in Japanese. I have studied Core 10k breakdown down to level 31, having no energy left to study down to level 1. Reading the post by Leebo gave me the idea. I might just study #1000 or #5000 frequency only. So, I exported the whole Core 10k excluding WK tag into the spreadsheet; and then sort by frequency column. I myself will study a limited list of L1-10, L11-20, L21-30. Please see if you find t…

Save that sheet as a CSV and then select to import items on houhou and select the CSV option. There should be instructions from there