is there function/operator/command that returns all members of a pool

This is making a fair number of assumptions about what you need to do, but it should at least give you a place to start:

https://devcentral.f5.com/codeshare/ps-pool-member-control

Note that this user is using iControl and Powershell to control his pool members.

If you are local to the bigip, tmsh show ltm pool members will return what you need to know. You can then use grep to pull out what you need.