Integration testing using PKCE with configured reponse types being code only

Hi !
Me and my team are wanting to create end to end integration tests for out aplication, protected by okta.
For that we need to find a way to get a tken from the okta auth / token endpoints.
The thing is our company enforced authorization through pkce with code as a response type, and we can’t really change that as it would be impacting the other company’s services.
What we want is to be able to use the pkce auth without the need to authenticate using a browser, we tried using a session token with prompt to none to no avail, okta telling us that the user is not loged in and we asked for no prompt.

Is there a way to do something like this ? The user actually was logged in using the /authn endpoint with credentials, so maybe i’m missing something.

here is the current state of our request :

requests.get(
        'https://login.vossloh-digital.com/oauth2/v1/authorize?'+
        'response_type=code&'+
        'scope=openid&'+
        'code_challenge_method=S256&'+
        f'code_challenge={code_challenge}&'+
        'state=TEST&'+
        'nonce=TEST&'+
        'prompt=none&'+
        f'client_id={client_id}&'+
        f'redirect_uri={redirect_uri}&'+
        f'sessionToken={session_token}'
    )

and we get this as a result :

The client specified not to prompt, but the user is not logged in.

Thank you.