So I released #halfposter (https://framagit.org/retiolus), my version of @spla #fullposter, it's a Mastodon <--> Twitter crossposter. By using any of the two, you do not give your access tokens to third parties, as they are stored on your machine.

Unlike fullposter, halfposter partially publishes your toots on Twitter, which makes people open Mastodon if they want to read the rest of your posts.