For Primal we are using UIKit because of the feeds with lots of different ways content can be displayed.

My opinion is that SwiftUI is getting better every year, so for simpler UIs it is already a good choice, and may even be a good choice for rich feeds in a few years, just not yet. Non-native is a good choice for personal projects or smaller apps, but many users will be able to tell the difference as it doesn’t feel as fast and responsive as native.