Oh wow, I didn't notice that it went to a canvas! Thanks for pointing that out. Definite consideration for whether or not to do use that in the future.
flutter is based on skia rendering engine and recently they added support for web assembly, it's a matter of time. the thing is, think in terms of capacity and vision, react native is done, flutter will move.
it doesn't look promising with the latest beef in the community and the last release notes that I saw in this project - to be real, they're laughable in comparison with flutter 1.9 changelog.