Currently there is no way to filter on items other than the label (as far as I’ve seen), but in our application it’s necessary to use a filtering service call.
I believe this feature is closely related to introducing lazy data loading, which unfortunately I haven’t had much time to look into. I am optimistic that at some point I will dig into these issues, as it’s quite a requested feature, but I cannot say with certainty when that will be.
I am currently working on a prototype lazy-loading support for this component. Hopefully, if all goes well and there are no major issues, I will release a preview version soon.