Hi Eric,
It seems you've managed to get everything working. It seems you're using OBJ C and I'm using SwiftUI, but could you please have a look at my posting below at tell me if you can point me in the right direction?
https://stackoverflow.com/questions/78981920/how-to-intgrate-passkey-in-ios-app-with-custom-python-backend-using-webauthn
Thank you.