I used to use an Anki deck with Kanji Stroke Order font which can easily cover up to the level of vocabularies as well, not only Kanji. There is this version for WaniKani in Anki – [Version 1.05 | 2016-01-31] Anki deck for kanji writing practice
Last time I tried, Kitsun doesn’t seem to have whiteboard feature; and I totally forgot about possibility of using Android handwriting keyboards. (While AnkiDroid (Anki for AnkiDroid) does have whiteboard feature.)
Japanese handwriting keyboard is always a possibility. I think Kanji are usually more similar to traditional Chinese variants, though.
There is also a trick possible with simply Excel or Google Sheets – Kanji / Explanations on column A-B, wider than the screen column C, Hints on column D. Then, try to work up 10 Kanji at a time. Colorize each row sets, if that helps.