There is no sane way of running automated acceptance tests for any of these canvas thingies. All existing test automation tools rely on proper DOM with even som

There is no sane way of running automated acceptance tests for any of these canvas thingies. All existing test automation tools rely on proper DOM with even somewhat semantic HTML. If everything is just canvas, we are back to image recignition and clicking by coordinates. And that is always extremely slow and brittle approach; one color change requires updates to many many reference images. Resolution/scaling/window size/window position changes coordinates. Etc etc. In practice there is no way of testing pages done using Flutter Web.