Since your needs are not specifically mentioned (other than cross-platform support), it’s hard to tell if Flutter may be what you are looking for. Will it require other dependencies? Etc.
However, from a generic point of view, I’ll say this:
I have yet to hear a Flutter developer not use the word fun when developing. I think you will like it as well. Since you have used Xamarin (and yes, Forms is not a great experience), I’ll assume you are comfortable in C#, Dart is similar and will feel fairly comfortable to understand. Take a few days to setup the environment and go through some tutorials, you will be pleasantly surprised.
I guess I could of asked outside of your question, it’s just I’m new to IOS and Android development and new to Kodeco… I too used Xamarin but way back in 2013 so I just have not heard of Flutter as I have not coded since 2016 and it was C#/ .Net