I've looked through all of the aux documentation but I cannot find any information on whether or not searching an item based on its item ID is possible. So for example 8846 for Gromsblood.

Using TSM's syntax of i:8846 or a search query of 8846 yields no results. In the filter builder there is no box to search by item ID.

Hey. This is not supported. Also, the blizzard api does not support it afaik, which means it would have to scan the whole AH (unless it would just convert it into a name search internally I guess), so I don't think it's a particularly important feature as you can easily look up the name online. I mean, I can see some minor uses, like sharing queries between people with different locales, and I guess there are no downsides, but I have extremely limited time at the moment so it won't be anytime soon.