Yes, it is possible. You may send a list of PSID (page-scoped ID) of the Facebook users to Sanuker. We will create an audience on Stella Push Panel for your use.
Once the custom audience list is created, you may send a push message to these users. If these users reply to the push message, they will become members of Stella.
However, if the users do not respond to the message, the users will not become members on Stella and you will not be able to send another push message to these idled users.
Please see the related documentation here.