Hello Connor,
the standard work on high notes is still, I dare say, Eugene Rousseau's "Saxophone High Tones" (1978). Rousseau's book includes the soprano. He even suggests special fingerings here and there.
The advanced exercises are absolutely frightening. In one (and many other) places, you find a note on the 4th auxiliary line (G) and after that, it parentheses, it says: 8 VA for that and all the notes that follow. I've been the owner of the book for more than 20 years. When I first got it, I quickly came to the conclusion that I would not do it in this life. Yet still, Rousseau talks about "successful students". (He used to teach as a professor at the University of Indiana). He admits that arriving at the high notes is hardest for soprano players.
None the less, I'd still recommend that you take a look because it gives very useful hints at airstream techniques and alternative fingerings, and teaches you how to get the ordinary high tones right (those that you still have keys for). The preparatory exercises (closed tube exercises) are useful not only for developing high notes, but also for arriving at a better tone in general.
Hope this helps.