2 Answers
It looks like I found the answer. In the console, they’re in the Info Panel of the compute instance. They can be retrieved using gcloud also but I was interested in seeing where they are. This tells me that they’re bound to the compute instance directly – maybe stored in a global table someplace but definitely retrievable through VM Instances.
If you are referring to the Billing Account related bindings (topic of this lecture), they can be created and accessed/edited via the console. you need to login using your admin account and go to the Billing Acct, where you can grant access to users/groups.