Is There a Way to Read the Frame Buffer Used by Flutter Canvas?

The Flutter engine has pretty tightly controlled access to its bitmap memory and its access to the GPU. So this has been a problem for Flutter processing, which is a package that I created. What I might do, in my case, is build a little static library in Rust, link that over Dart FFI and use that to paint individual pixels as much as possible. But until the engine kind of shares control of its bit map memory, I'm not sure what any of us can do, unfortunately. We're just stuck paying that penalty.