isn't ublock's filtering compiled to webassembly?
From my unprofessional glance ar their repository, it uses a little, but not much. Take a look at their code; all or most of the filtering is done in JavaScript, the webassembly appears to be just one two modules. (It's in the "wasm" folder near the top of the list).
(Edit: I was looking at outdated code; the newer version uses more, but IMO pales in comparison to the JavaScript filtering logic)
seems a bit dangerous though to risk for a browser with so small market share
Waterfox has a much smaller market share and much smaller budget, and was able to clear this with search partners just by promising not to block ads on them by default.