My friend qualifies for the delta ring, but it’s not available for him?

That feature is only available to Alpha,Alpha skip aheads & Beta Insiders at the moment.

As you are in the Delta ring you will still need gold to play any games online.

I am currently trying Delta ring. I will report here if it helps with crashing in late game.

UPDATE:

I was able to finish the game that was constantly crashing after updating to Delta ring release Xbox Insider Release Notes - Delta (2208.220715-2200) - Xbox Wire

If Omega ring has same fixes, then hopefully everyone will get this fix soon.

I will continue testing with Delta ring with all addons enabled (currently have extra civs disabled) with new game on huge map.

The Chromium browser was previously only available for members in the Alpha Skip-Ahead ring, but as of the last couple of days, it's not only been rolled out to Alpha members, but also Beta and Delta members. Only the Omega rings have yet to receive it.

Status July 2021

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.

It was also released to Beta an Delta rings on 31st October 17