I'm potentially the only one being skeptical. Don't get me wrong, it's nicely done (for an experiment), but we also did similar experiments several years ago.
At the fundamental level such an approach works, but it brings several issues that are not addressed with it (in contrast to, e.g., Electron). The most pressing one being "I don't want any browser - I want a browser that I know is capable of doing what I want".
So most of these techniques used to have the problem that on Windows "any browser" was always "Internet Explorer"; but while I don't disagree that this is still an issue, it is much much much less of an issue now that Internet Explorer is Edge and Edge is Chromium (which I am not saying is a good state of affairs for the web as a whole, but makes this use case not fall as easily to this complaint).
But I don't think Edgium is replacing Edge/IE as the system web component. It's no different than having Chrome installed except it replaced the Edge icon in the start menu instead of making a new one.
I'm skeptical for a similar reason. This isn't really "crossplatform" it is "capable of running on a very small list of platforms which bundle a web browsing component."
At the fundamental level such an approach works, but it brings several issues that are not addressed with it (in contrast to, e.g., Electron). The most pressing one being "I don't want any browser - I want a browser that I know is capable of doing what I want".