Hi Mario,
Greetings from Syncfusion.
We have checked your requirement from our side and in our current implementation, we do not have support for loading ActivityIndicator in SfAutoComplete DropDown. We have logged a feature report for the same. You can find the feedback link details from below.
Please cast your vote to make it count. We will prioritize the features every release based on the demands.
If you have any more specification/suggestions to the feature request, you can add it as a comment in the portal.
Thanks,
Muneesh Kumar G