Using DO Apps, how to open TCP port?

Trying to expose a TCP port for a node-red flow for some colleagues. This should be dead simple. The port I’m trying to open is 3333. Port 80 seems to auto-map to the typical http port 1800 and I can access the standard web editor via port 80. I tried this internal_ports you see at the bottom, but that isn’t working:

alerts:
- rule: DEPLOYMENT_FAILED
- rule: DOMAIN_FAILED
features:
- buildpack-stack=ubuntu-22
ingress:
  rules:
  - component:
      name: nodered-node-red
    match:
      path:
        prefix: /
name: scalesim
region: nyc
services:
- http_port: 8080
  image:
    registry: nodered
    registry_type: DOCKER_HUB
    repository: node-red
    tag: latest
  instance_count: 1
  instance_size_slug: basic-xxs
  internal_ports:
  - 3333
  name: nodered-node-red

Can someone advise how I might change this App Spec so that I can test the 3333 TCP port listener in my flow?