It might be difficult to impossible to currently implement, but perhaps if you have access to :///* you should lose access to pretty much every other permission.

I think it's better to implement content blocking outside of the browser (especially considering it's not in the interest of the most popular browser's backing company) and eliminate these types of permissions completely! I.e. Wireguard + DNS adblocker (or w/e you want to block). Not only does it perform better but you aren't leaking data to third-parties, who even if they are noble could be acquired by a less noble entity down the road.