Hello @Michael Moles
welcome to this moderated Azure community forum.
The short answer is that Debian 9 Stretch is not mentioned in the Tier 1 or Tier 2 supported platforms.
Tier one platforms are tested by Microsoft.
Tier two platforms are considered compatible because customers have acknowledged it runs Azure IoT Edge.
Still, you could be lucky is the hardware specs are good and you are creative with the OS settings.
On June 30, 2022 Raspberry Pi OS Stretch was retired from the Tier 1 OS support list. To avoid potential security vulnerabilities update your host OS to Bullseye.
If you can update to Bullseye, it is recommended.
If you get it running in a secure way, please share a blog post for the community.
If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. All community members with similar issues will benefit by doing so. Your contribution is highly appreciated.