Add the finance team members to the Billing Administrator role for each billing account they manage. Add developers to the Viewer role for the Project.

Add the finance team members to the default IAM Owner role. Add developers to a custom role allowing them to see only their own spend.

Add both developers and finance managers to the Viewer role for the Project.

Add the finance team to the Viewer role for the Project. Add developers to the Security Reviewer role for each billing account.