Hi, @cedaly.
Could you describe exactly what functionality you’re seeking?
It’s already possible to create and update custom product properties via API, but not in the UI.
There are plans to add UI functionality, but I currently can’t offer a concrete timeline. To hasten the process, please upvote and comment on this idea specifying the need for UI support. You an also subscribe to the API Changelog to stay notified of updates.
You can also segment lists and workflows by custom product properties, per the GIFs below.
List segmentation
Workflow segmentation