Looking to implement OpenZiti to 20k IoT devices, seeking help

I have a design and looking at 2 technologies (OpenZiti and Nebula) to see if this would work for connecting 20k IoT devices. Currently we use OpenVPN which works great but the setup is ok and not perfect. It gets the job done. This is where I am looking to see how OpenZiti can help with this setup. I have OpenZiti setup internally for our developers and works great! Have not had issues at all from developers. Nevertheless, I do have questions for this feat when it comes to our 20k IoT devices:

  1. How does OpenZiti handle cellular data where there can be disconnects and reconnects after 12 hours to more than 2 days of disconnection/reconnection?
  2. Does OpenZiti utilize NTP servers to keep in sync with the clients when communicating back to OpenZiti?
  3. Does OpenZiti support DNS servers as well for easier sshing into these devices?
  4. How does load balancing work? I know you have HA clustering which is still confusing to me in documentation. Tried setting this up myself and caused it to crash on several occasions.