The most important thing that comes to my mind, reading the Block Protocol docs, is how they focus on blocks as paradigms for content types (implemented by React (like Gutenber), Vue or Web components), while Gutenberg has so far ignored structured content, leaving folks to turn to 3rd party plugins like acf, pods, toolset, etc. Integration of Gutenberg with Block Protocol could be a big deal in rectifying the horrific omission of in-core content type management in Gutenberg so far.