> The ecosystem is immature
There are usually good libraries for most things today. And with Android / Jetpack ecosystem moving so fast and deprecating things, Flutter is something to consider even if you target just Android.
My biggest two concerns were state management and native interop.
State management is probably biggest concern - there are at least 5 approaches / libraries competing for mind-share - and none of them are particularly ergonomic.
I did get an opportunity to work for a while on native interop for android / java [1]. But I haven't been able to work on that since long time.