Rendering a QQuickItem into a QImage in Qt6 can be achieved by redirecting rendering in Vulkan to a VkImage using QQuickRenderTarget. Have you tried using the suggested approach with QQuickRenderTarget::fromVulkanImage, and if so, what issues are you encountering in your implementation?

Additionally, have you considered other methods or libraries to achieve your color picking in a complex 2D scene, or are you focused on solving this within the Qt framework?