Please let us to link a custom entity like a template (or a spare entity) to a device, to better organize all the entities.
This could be done in conjunction with a custom device creation, where we can manually join entities.
A simple use case: a device that come with numeric entities, where I need a binary sensor based on that entities. I could create a simple template but that template entity never be shown in my device, actually… With that feature request I can choose to link it to my device.