At this stage I have not found a way to open PDF files directly in Adobe Reader, however Microsoft have recently announced that the Edge Browser will start using Adobe Acrobat PDF engine soon.
To meet the needs of organizations with managed devices, the
transition to the built-in Microsoft Edge PDF reader with the Adobe
Acrobat PDF engine will occur in phases:
- March 2023: Unmanaged device rollout will begin in March 2023. Managed
devices can opt-in using policy via Intune.
- September 2023: Rollout to
organizations will begin no earlier than September 2023. Organizations
with managed devices may opt out of this experience via Intune policy.
- March 31st, 2024: The legacy PDF engine in the Microsoft Edge PDF
reader is scheduled to be removed (and opt-out no longer available) on
March 31st, 2024.