Correct

> Am I right that WebKit does not support what you and I are discussing equivalent wise? Passing structs or "binary" events?

I'm not sure. If I wanted to do this I'd probably look into https://ultralig.ht/ which is a commercial fork of webkit. See: https://docs.ultralig.ht/docs/calling-a-c-function-from-js

I'm probably being conceited but the fact that some company somewhere thought it was a good idea to add this feature for commercial efforts probably makes me think it's missing from the open source world.

Given your knowledge on Dioxus, do you think Dioxus/Tauri/Wry will eventually support something like this? I guess it's kind of niche.

Something webkit based? Almost certainly not from a Dioxus perspective. We may add JavaScript support to Blitz at some point though. I believe Tauri have been looking at a WPE backend which may be able to support these kind of things, but I wouldn't hold your breath.