This example from the HTML5 spec has the datalist providing values for the range control, but having no UI of its own. In this case, it would not be mapped to the aria listbox role. I think it would not be mapped at all, only providing value data to the range which is then mapped as a slider. Are there other examples of where datalist is not a listbox?

<input type="range" min="-100" max="100" value="0" step="10" name="power" list="powers">
<datalist id="powers">
<option value="0">
<option value="-30">
<option value="30">
<option value="++50">
</datalist>

https://www.w3.org/TR/html51/semantics.html#range-state-(type=range)