Flutter has a very good plugin architecture. You don't actually have to use their widgets if you don't want to. And as for being restricted to the prevailing platform paradigm ... you have as much freedom as the platform gives you. For some things Flutter can't provide miracles ... like to access specific device hardware you are going to have to build a native bridge ... but in the end Flutter is building a binary that is ... as much as possible ... standalone. It even reinvents GUI components instead of bridging to the prevailing OS ones, touch input instead of using the native one, etc., so that you have more control (if you want it).