Not that it would change FB's mess of an algo, but you probably can achieve some results with uBlock's custom filters, which are mostly written in CSS selectors

Not that it would change FB's mess of an algo, but you probably can achieve some results with uBlock's custom filters, which are mostly written in CSS selectors. Find out the classes that shared posts get and slap them in the filters. There are also the ‘:has()’ selector and the search-by-text ‘has-text()’ selector to filter parent nodes by child nodes' content.