I don't know any readymade example, but this sounds like something that'd be reasonably easy to hack, maybe with a browser plugin/user script for an existing service, or as a slight modification of a self-hosted open source one?
EDIT: just checked it out using dev tools, seems like in inoreader a userscript only would have to remove some onclick handlers to get links instead of previews.
EDIT: just checked it out using dev tools, seems like in inoreader a userscript only would have to remove some onclick handlers to get links instead of previews.