Hey there - Flutter team member here. Support for integrating arbitrary non-flutter views/widgets (referred to as PlatformViews in Flutter terminology) is something we're actively working on at the moment, once we've got them landed, web views and video player support are top of our list in terms of views to add support for. We know people can't wait for this to land, and believe me, I can't wait for it to land either :)
PlatformView support is one of our top desktop priorities this year (along with multi-window support).
PlatformView support is one of our top desktop priorities this year (along with multi-window support).