> Like, a browser that only runs wasm
That's not a browser.
More or less by definition, a browser is an application that can use HTTP (and potentially other protocols) to make requests to other systems and retrieve stuff described using HTML (and possibly other formats).
Sure, a tool that just loads wasm and executes it would be fun (and probably exists, at least for the local case). But it's not a web browser.
As opposed to current browsers that run wasm and JS I mean
Yes there would be a DOM in addition