As far as I know, Edge doesn't support the image-rendering CSS rules. Pixelation even has the old IE-specific "-ms-interpolation-mode: nearest-neighbor" rule, but Edge doesn't support that either.
There's no solution*, you should use another browser for browsing pixel art sites. image-rendering support is on Edge's roadmap, but it's not a high-priority feature.
* There is technically a solution: using JavaScript to do the scaling. This is overkill, especially since most browsers do already support nearest neighbour sampling in some way.