The problems we had is users could not reliably tell when they were connected/disconnected, how to initiate the login flow, get network status (why is that service not working, but this other one is?), tell to which router they were connected, etc etc. I know these are big asks, and I suspect a lot of these troubleshooting and status info are probably available in the commercial offering.
That being said I think OpenZiti/NetFoundry is in a different class entirely and any lurkers here should consider it for their use. It's not really the same thing as NetBird or Tailscale.