You have not said what platform you are developing for, but let's assume iOS (or iPadOS, but the same principles apply to macOS).
If you are serious about using MapKit, and want to go beyond very basic mapping functions...
...then handle your map using UIKit, not SwiftUI.
Mapping in SwiftUI is still lacking a lot of features which you may need, and if you start off using SwiftUI, then run into it's limits, you may have to begin again.
I love SwiftUI, but it's mapping is too weak.
On macOS I use Cocoa (NSViewController) for maps, wrapped in an NSViewControllerRepresentable.
I found problems when using NSViewRepresentable, so I don't use that.
(On iOS, the equivalent to NSViewControllerRepresentable is UIViewControllerRepresentable.)
If anyone disagrees with this, then I would love to hear their better solutions!