Unfortunately the DOM APIs were specified to have Javascript-specific details in them. As far as I understand it, the best way to access the DOM from WASM would be to define a new WASI Component -compatible API for the DOM.
Nobody's done the work yet, and I think the current strategy is to tackle easier APIs first, as WASI might not be good enough to describe the DOM at this time.
With a DOM API independent of Javascript, you could have a C/C++/Rust DOM in the host, and C/C++/Rust code inside WASM calling functions on the DOM, without needing to talk about Javascript types in the middle.
Nobody's done the work yet, and I think the current strategy is to tackle easier APIs first, as WASI might not be good enough to describe the DOM at this time.
With a DOM API independent of Javascript, you could have a C/C++/Rust DOM in the host, and C/C++/Rust code inside WASM calling functions on the DOM, without needing to talk about Javascript types in the middle.