If you use Color Sets in the Assets Catalog to define your color palette, make sure you enable variants for the Any, Light and Dark appearances and also High Contrast. You'll be able to define variations of the color that have better contrast.

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VoiceOver will traverse elements from left-right, and from top-bottom. If for any reason you need to change that order, in SwiftUI you can change the accessibility sort priority. A higher priority number in the container means it will go first.
To capture the gesture, you can override the accessibilityPerformEscape() function. In there you can dismiss your view, and return true if you could successfully handle it. https://developer.apple.com/documentation/objectivec/nsobject-swift.class/accessibilityperformescape()

When configuring a largeContentImage or adjustsImageSizeForAccessibilityContentSizeCategory, it is important to use a pdf asset and preserve the vector data so the icons are crisp at any size.