I'm starting to love Flutter, but I'm afraid to invest in it -- Google has a history of abandoning projects they get bored with. I took a long time to come on board with Golang for the same reason...
Unless Apple starts implementing its own cross-platform sdk in swift... But judging by the slow pace at which swift is moving (compared to its "worl domination" ambitions, that is), i don't think it'll happen anytime soon.