openHAB Cloud: trouble understanding current state of ecosystem

If you go at the end of the issue you linked, you can see that all the workarounds that were applied didn’t resolve the root cause and that it seems that the default buffering feature on the cloud connector nginx instance may be the culprit.

This is unfortunately the only workaround for your issue.

This is correct. During the discovery process, the full list is required to determine which items are Alexa-enabled.