In general, people use any image host that allows hotlinking, and then embed images in their post using img tag. When viewed inside a Pixelation page, embedded images are clickable to zoom (and ctrl-click / shift-click to unzoom, alt-click to reset to 1:1 size). Pixeljoint forum has similar feature.
Anybody has experience with lospec as image host ? From what I can see, they support hosting image without needing an account, allow hot-linking, and provide a standalone page that supports pixel-friendly zooming. (mousewheel, drag to scroll)
https://lospec.com/i/bynbOn pixel-friendly sites, zoom is non-blurry thanks to some CSS that is supported by most web browsers by now, but still not all.
https://caniuse.com/#feat=css-crisp-edges