Thanks for contacting Syncfusion Support.
We have checked your query. Currently we does not have support for change the appearance for the PullToRefresh circle view. However, we have planned to provide the template support to load custom view for showing progress in SfPullToRefresh. So you can load the any view inside the template. It will be available on any of our upcoming volume release. If your requirement is different from this. Please revert us with clear requirement details.