Only Omega showing when picking release rings?

The new update is only out for some Alpha & Alpha skip ahead insiders at the moment.

If you're in the Omega ring then you'll probably be the last ring to get the update before it's released to everyone.

It looks like it hasn't been released for the Omega ring yet. Hopefully soon!

Today the Chromium browser is released in the Omega ring to al Xbox users........ Finally .........

In my understanding the Dashboard experiment, A, B, C selection, is totally random.

As "Both consoles say their OS Version is (19h1_release_xbox_dev_1911.191028-1335)" your consoles are either in the Beta or Delta ring.

Both those rings and Omega ring are getting a preview update News release notes Beta Delta Omega
Insiders today, which you can manually start or wait until it becomes mandatory.

After you do the update, if you want to change rings, it will be the perfect time to change as all those rings will be on the same release. Subject to eligibility.

If you are part of the Insiders preview program, consider going to a ring which has less frequent updates, like Delta or Omega.

Alternatively you can unenroll from the program, so you only get GA (General Availability) updates when they are released.