Just for fun, I listed out every single view transition that happens during onboarding, including every fake-out the app does. This is the UI version of telling a story to your friend but going on constant tangents and finishing the story 20 onboarding steps later.
Since this is someone's first impression of your app, it's SO important to show a clear navigational hierarchy. Where views come from, what happens when they get dismissed, etc. When sheets slide in and out and content flashes for half a second, that mental model quickly rots.