Moving to the next ring in insider

One thing to be aware of, you must be active in the insider program for a while, and be selected for the alpha ring. You will likely start in the "Omega" ring, and after 1 month you can move up to the "Delta" ring. 3 months will get you
into the "Beta" ring, etc.

I never got an invite but just kept checking the Insider app until the option to move to the Alpha Ring appeared.

It doesnt ruin the game, its fine. The Next only appears within 10 seconds left in the ring. Thats usually when people decide to move away and look for the next ring. Quit complaining.

You could try uninstalling the insider app and reinstalling it, sometimes there can be issues server side when you move rings

If your friend is in the Xbox Insider Program, it might be that the Guide re-arrangement feature is currently in testing for the Alpha and Alpha Skip-Ahead rings. He could start the Xbox Insider App and check which ring he is enrolled in.

If he's eligible, he might have the chance to move up to an Alpha ring, but also at the risk of new stuff not working. So he should really consider if it's worth moving up to a less stable ring.

When that new feature is being released to lower rings or the general public depends on how many issues the Alpha Testers find with the feature.

Only if it's considered to run stable, it'll be released to lower rings or for general availability.