If you want to track revenue tied directly to work completed by agents, then the Revenue by Service Agent report should do just that. It might not match up with other revenue reports but that's because not all revenue was directly created by an agent.
Revenue by Service Agent is essentially all invoices that can be directly tied to an appointment the agent worked on. So this basically means any appointment that was finished and produced an invoice as a result of finishing would be included here. So the Total, marked in your screenshots, will be the total amount from invoices generated directly from finishing an appointment.
Other reports like Revenue at a Glance does both backlog (incomplete appts) and invoices. The backlog is just the Total listed on any unfinished, not cancelled appointments. Invoices is just all invoices.
This method would allow you to pay based on the production.
(Update 12/12/24: Our team has made a request to the Serviceminder dev team to build a payment-by-production feature into the setup of a service agent account. No timeline, yet, for deployment, but the hope is in time for the 2025 season.)