Hmm. Well, Celan very much does have something left to say. That’s why he wrote Todesfuge. That’s why, when asked why he wrote in German, he said I’m not going to let the Nazis steal my language. I’m not sure of your Celan point.
Update. Here's Celan's Todesfuge, in English then in German:
https://poets.org/poem/death-fugue
Oh, and now seems a good moment to mention Nazis, with Putin calling Zelinskyy a Nazi. The man is a grandson of Holocaust survivors. Zelinskyy is not, in fact, a Nazi, that seems like something left to say.
Cheers,
John