How to deal with optional form step & call-to-actions?

Situation is as follows:

A user responds to another users request with some details of his offer. Some of these details are required (step 1) and some are optional, but help the requester even better (step 2). After these steps, the input he provided gets sent to the other user & saved for future inquiries, and the users are introduced in the chat to each other.

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What's the most clear way of communicating to the user, that in step 2, both actions send the user to the chat, while still trying to persuade the user to fill in the optional details aforementioned?

CTA's should be as concise & clear as possible, but I'm faced with the problem of putting 2 actions in 1 button to clearly indicate the next step for both CTA's, e.g. 'Save and chat' + 'Skip and chat'.