Binaries in Dart are definitely larger than 200kb, I just AOT compiled one of the examples and it was ~7.4MB (arm64 MacOS). Dart has a few different targets it can compile to, but it generally requires a couple of MBs, as it packages the whole runtime.
Yeah, my goal definitely is to have to as close to Flutter where it makes sense. You should mostly be able to copy it over 1:1, with a couple of caveats (GUI and a TUI app have a few differences here and there).