can we configure the port that FleetDM listens on? maybe via env variables?

Yes. See https://github.com/fleetdm/fleet/blob/master/docs/2-Deployment/2-Configuration.md#options

hmm i only see port options for mysql and redis, does fleet dm itself listen on any ports that we can configure?

Yes, check out

server_address

here https://github.com/fleetdm/fleet/blob/master/docs/2-Deployment/2-Configuration.md#server_address

ah ok, im blind haha, thanks!