If you’re still up for suggestions, I have another one.
Add the option to put the radicals and kanji in the reviews in the beginning. It can be all radicals and kanji like in this script or just from the current level like in the Wanikani customizer. Whatever you feel is better/easier to implement.
I rarely feel like doing or have the time to do many reviews on my phone but just doing those “level critical” ones would be immensely helpful.