This morning the Elizabeth Line fares are on the TfL single fare finder. Unfortunately the TfL journey planner doesn’t have them or the Elizabeth Line services.
National Rail does better but is missing some of the interchanges such as Moorgate and I’ve spotted some incorrect fares (I assume) where it is offering Paddington via Farringdon or Liverpool St. at the London Terminal fares from Thameslink and Greater Anglia stations