Thanks for your reply and Our requirment is to send email to workqueue users and any user mapped to that queue can take action(Approve/Reject) from the email they have received and case flow has to move to next step automactically.
Email Approval flow is option is available & supported while Routing to "Specific User" only.
Your initial question was to approve/reject without logging into Pega.
Users mapped to work queue (Pega) is a relation maintained in Pega and you still want one of these users to approve/reject from email only? If yes, we can only send email approval to a person(email address). Work Queue will not have an email associated.