The #VivaldiBrowser is the closest thing we have to an “swiss army knife for the open Internet” today, and yet it doesn't even have feature parity with the late Opera/Presto. For example, it has no IRC client.
But in the context of my vision for the #Fediverse, the most glaring omission is the lack of an equivalent to Opera Unite, an incentive to the development of easy-to-deploy self-hosted websites.