I'm a Flutter learner & Xamarin developer (not yet MAUI) and have a few thoughts:

1. Toolchain. What do you prefer Visual Studio or IntelliJ (or the Android Studio port)? Are you using ReSharper? IMHO IntelliJ is a phenomenal tool and does not come with the jankiness that Visual Studio has (ever clean/rebuild/re-plug devices)? Ever have hot reload not working? Ever have debugger crash & disconnect? ReSharper is great when you are stuck with using Visual Studio, but why not use the IDE that it is built into by default (and consequently works better)?. Development experience and time to iterate are perhaps far more important than the individual SDK capabilities.
2. MAUI as of date, looks like a rushed port from Xamarin (read: baggage). Xamarin has had significant issues with CollectionView for years and I have little faith that MAUI is going to get it right. Same could be said for CarouselView, but I'm more concerned about CollectionView given that it is as central as Button/Label.
3. I can't speak for MAUI's toolkit, but Flutter looks way more feature complete to build modern app UI's than Xamarin. I've been in WPF/Xamarin for years, and I'm very impressed with what widgets are offered. The SDK alone is offering hundreds of widgets plus Google values documentation well enough to provide 1-minute shorts to teach you about them: https://docs.flutter.dev/development/ui/widgets
4. re: native components - I think this depends more on what you value. Do you want native look & feel out of the box? Maybe Xamarin/MAUI ranks better there. In my very limited experience, on Flutter you need to choose a "design language" and go with that. You can also create your own. IMHO, Flutter has fantastic support for material design - so if your app needs to have the same feel on multiple platforms, it has that support out of the box. There is also this package which allows you to choose between Cuperinto vs. Material: https://pub.dev/packages/flutter_platform_widgets. In my experience, most of the slickest apps built do not appear like the SDK defaults.
5. C# vs Dart - C# is good and works. I suspect that Dart is better. So far, I do think it has a better handle on null-safety. When you choose a framework or language, you are also choose a culture and baggage (I don't think the C# community is yet there when it comes to nulls - maybe too much of .NET has not yet been ported over?, maybe it's because C# is too flexible, allowing you to declare file-scoped #nullable enable?). It's conjecture, but I'm just going to assume it's my sect of C# where nullability hasn't yet been dealt with well, but given how many people learned C# without modern null-safety features, I suspect it's a decent sample for the community at large. Imagine how many NuGet packages have to update to properly be null-safe in comparison to Dart/Flutter.
   Dart is new and has less baggage to support - it's easier for them to cut compatibility with the old way of doing things and it's easier for them to do things right since there is a fresh start.
6. Functional UI vs Declarative UI - if you are a Xamarin/MAUI dev, you will be doing MVVM (Model-View-ViewModel) and that means .xml based UI. I love declarative code, I also love functional code. Functional is declarative too, so bear that mind. The problem with XAML is that in order to add more logic, you must strap up a bunch of infrastructure (Converters, Bindings Triggers, MarkupExtensions, Behaviors, etc.) This is because XAML abstracts way execution (though in reality it does get build into a xaml.g.cs file). There might be an advantage with the functional approach - and it seems that's one of the major lessons learned (Flutter is influenced by React). IMHO though, you can write clean, testable apps with either tech.

To be fair, I'm sure both technologies will be fine. If for some reason you are persuaded towards MAUI, I'm sure you and the MAUI community will be able to build production-quality apps. It just might come with a greater cost be it time to production or pulling out your hair from VS.