The key to something like this will be importing csv files into anki and making sure that the first column matches existing cards so that you can update existing cards instead of overriding them. (ok, well either that or doing it immediately in your google doc; you would need a separate sheet with the WK vocab info first and then you could combine the info from those two sheets using VLOOKUP; go look it up, it might change you spreadsheet life )
Once you have your complete vocab list in an anki deck (first firld should be the vocab in japanese), you import a list that contains wk vocabulary in the first column and e.g. „level6 wanikani_vocab“ in a second column. you would chose to import this as the same type of card as your existing deck and select „update existing cards“. the second column is imported as tags (but you could also just create a separate field for this info). then you can filter by these tags and suspend all cards that are tagged „wanikani_vocab“.
I did something similar for adding WK and JLPT level info to my core 10k deck.
There is a wanikani to anki exporter somewhere that you can use to get vocabulary with level info I believe. Or existing WK vocab decks that you can first import and then export to csv if needed.