Is it possible to create email group based on formula field?

I have two fields:

1. CT APPROVED APPROVER ROLE = list of roles if they have approved a vacation request
2. CT REJECTED APPROVER ROLE = list if they rejected request

Currently, those fields only have data added when a decision record is created and status is changed to either Approved or Rejected.

I need to create a reminder email that sends after 2 days to those approver users that haven't approved or rejected a request (basically have request pending approval).  

Do I have to use a pipeline I previously created to automatically create decision records for each role to be able to create the email group for the reminder or can I do it without the pipeline?  And how would I script the formula?

Hope this makes sense.

Kim