[Question] Why isn’t there a charity evaluator for longtermist projects?

i.e., Why isn’t there an org analogous to GiveWell and Animal Charity Evaluators that evaluates and recommends charities according to how much impact they can have on the long-term future, e.g. by reducing existential risk? As opposed to only making grants directly and saying ā€œjust trust usā€ like the EA Funds.