Hi on WaniKani stats if you go on the wanikani page from the items option at the top, you can actually filter out most things by setting primary and secondary to none and hiding the locked and lesson items to show you which kanji you’ve learned out of the one’s available as below:
Also, if you prefer another website, there is a really great tool made by @tylercarty called WaniTrack at I built a WaniKani Stats Tracker with some features i thought were missing… which shows a lot more details as well.
Hope this helps and have a great rest of your day!