We may not even need Object aggregate; I don’t have a specific example to provide, it is just there for completeness.
Re: Device v Consumable, US billing is just an easy way to understand the difference; it’s universal. And you are right, there are disposable ‘devices’ so we may need better terminology at this level. However, ‘Device’ is a commonly used term in HL7 and health data in general, and consumables are generally distinguished from non-consumables. We can certainly improve the modelling.
There is no doubt that this part of the model is not for all users of openEHR, but there are quite a few who want it, and to implement Task Planning with even basic resource tracking it has to be solved to some level.