Hi Paul,
Greetings from Syncfusion.
We have checked your reported query “To expand a top entry in the accordion on mouse hover”. And this can be achieved by creating a custom control by inheriting the SfAccordion in code behind and then the top entry in the accordion can be expanded by setting the SelectedIndex to 0 in PointerEntered event and collapsed by setting SelectedIndex to -1 in PointerExited event.
Sample link:
https://www.syncfusion.com/downloads/support/forum/169576/7z/Accordion-452166571 Please let us know if you need any further assistance.
Regards,
Arunthivakar A.