Default display is not compliant to allow screen reader or keyboard control of accordion rows or content panels.
View any accordion view display and attempt to tab into it to control content.
Extend default displays and templates with additional behaviors to monitor state and status using ARIA attributes for screen readers.
https://www.w3.org/WAI/ARIA/apg/patterns/accordion/
I've attempted to attach a add-on module which perhaps the maintainers could integrate into the official releases.
Needs review
2.0
Code
Found a bug where the group custom template was rendering on all grouped rows instead of explicitly only for views_accordion row format styles. This newer version correctly loads the group template only on views using the views_accordion format style.
Works great!