Hi John,
I assume you’re planning to distribute the ISO in advance so you can either schedule the in place upgrade or allow the user to initiate the process.
There some prereq checking that you’ll need to do, including verifiying disk space, and whether there is enough space in the reserved partition on UEFI systems.
I would recommend looking at the fixlets in Patches for Windows - Windows 11 Business Editions Version 24H2 Available. They are a good starting point for your project.
You can clone the fixlet, and modify it for your ISO, if needed, along with stripping out the action script that performs the upgrade process (You should also consider using the File Pre-Cache Wizard from BES Support),
Then you can take action on the modified fixlet to begin the file delivery process.