Feature: consider using Popover API instead of `aria-expanded`

### Is your feature request related to a problem?

See:

- https://developer.mozilla.org/en-US/docs/Web/API/Popover_API
- https://codepen.io/MrGrigri/pen/yyYvRJr
- https://chrisburnell.com/html-can-do-that/#popover
- https://adrianroselli.com/2026/07/link-popover-navigation.html

### Describe the solution you'd like

Evaluate the Popover API as an alternative to the use of `aria-expanded`. Consider browser support and accessibility implications as well as any other factors.

### Describe alternative solutions you've considered

Maintain use of `aria-expanded`.

### Additional context or notes

_No response_