Are there any good prior discussions on grouping elements inside of a combobox, either in ARIA or HTML datalist? Not much I've been able to find that goes too deep on the topic.

- datalist doesn't support optgroup, though there have been hacky workarounds and one limited, closed issue in the w3c repo requesting it

- ARIA spec doesn't mention grouping in the context of combobox. It's permitted in listbox generally

In most examples I find, the groups have no affect on filtering/matching logic. I wonder if there's a case where it might reasonably be expected that they do, and if so, what are the accessibility implications?