Balancing screen-reader announcements and visual stacking in MatSnackBar

MatSnackBar provides transient notifications that appear at the viewport edge and auto‑dismiss, but screen‑reader users often miss the message because focus is not moved and no ARIA‑live region is guaranteed.

The configuration options available (panelClass, position, duration, data) do not include a dedicated flag to force screen‑reader announcement, and rapid successive openings may cause visual stacking that adds noise.

Which MatSnackBar settings can reliably trigger a screen‑reader announcement without altering keyboard focus, and does any existing panelClass or data property support this purpose?