Just use the same {{ csrf_token }} twig function to generate the stateless token and the same isCsrfTokenValid() method from AbstractController to validate stateless tokens. These functions are designed to fallback to the stateful CsrfTokenManager if they detect that the token ID is not stateless. They're designed to work for both stateful & stateless CSRF protection depending on the form. You just need to make sure the token ID is part of the stateless_token_ids array in config/packages/csrf.yaml (which it already will be for the Symfony Forms component if you used the starter project from Symfony 7.2 or later).

I wrote an article explaining how stateless & stateful CSRF protection works in-depth in Symfony because I wanted to know myself. If you're confused, this should help.