AWS Workspace Pools - Application Persistence - File Type Associations

A group policy will overwrite user changes and that is how group policy works. An alternative is if you can find the registry key for the setting and then use group policy preferences in Apply Once mode. The challenge here is Windows now has a habit of restoring default applications to Microsoft application .e.g. Edge which is probably why you used a GPO in the first place. Non of this is unique to Amazon WorkSpaces. Settings persistence will save anything changed in the user registry hive, however, group policy will overwrite anything saved in the profile.

Yes, Application Settings Persistence in WorkSpaces Pools should store and remember user preferences for File Type Associations.

When you enable Application Settings Persistence for WorkSpaces Pools, it saves the HKEY_CURRENT_USER registry hive for the user, which includes file type associations. These settings are saved to a Virtual Hard Disk (VHD) file that is uploaded to an Amazon S3 bucket in your AWS account and synchronized between sessions.

Application Settings Persistence is designed to save application customizations and Windows settings, including browser favorites, settings, application connection profiles, plugins, and UI customizations - which would typically include file type associations.

If your file type associations for PDF files (changing from Chrome to Adobe Acrobat) are not persisting between sessions, this could indicate an issue with your Application Settings Persistence configuration. Make sure that:

1. Application Settings Persistence is properly enabled for your WorkSpaces Pools directory
2. The VHD is being properly synchronized to S3 between sessions
3. There are no policies or scripts running that might be resetting these associations

For compute-intensive applications or situations where persistent storage isn't performing as expected, AWS recommends using alternative solutions like Amazon FSx for Windows File Server or AWS Storage Gateway file gateway, but file type associations should be covered by the standard Application Settings Persistence feature.
Sources
Enable application settings persistence for your WorkSpaces Pools users - Amazon WorkSpaces
How application settings persistence works - Amazon WorkSpaces
Enabling application settings persistence - Amazon WorkSpaces
Enable and Administer Persistent Storage for WorkSpaces Pools - Amazon WorkSpaces

Do ensure that application persistence is enabled as per documentation.

Note these settings are stored in a VHD. The default size is 5 GB. On some occasions, you may have to increase the size in order to allow settings to be saved successfully.