I don't really have a good mental model of how ports/files/etc get exposed/permissioned across users. Containers and sandboxing seem much more common than agent-user accounts. Networking seems a little more complicated in the general case.
I roughly went the route of running apple's container-cli (separate vm/kernel per instance I believe) and mount the relevant home directory/projects and bind ports. Seatbelt/linux sandboxing seems simpler sometimes, but has its complications too.