Most of the initial innovations seem to be in the hardware, e.g. controllers that hop over your PC/console, game servers in edge nodes, etc. They're incremental improvements, but my latency on Stadia gets down to single-digits at times (though is usually low-mid double-digits), which is something I never saw with OnLive (not a direct comparison since I have better Internet now).

There's some interesting software innovations that may or may not be implemented (I'm not sure?), but I haven't heard of other streaming platforms doing things like running games at significantly higher framerates (to minimize the time between player input and game response) and predicting button presses to buffer a stream before they happen. Those seem like innovations in the space, even if they're under a terrible umbrella of a name ("negative latency").