Hi @Adamh44
I'll try my best to answer but our expertise mostly lies within Project Firefly, and I do not know the best answer for integration pattern with Target / AAM. If you are an existing customer, perhaps you could try the Target forum or reach out to your customer manager to meet with a Target specialist?
From Firefly's perspective, it sounds like you want to add an additional profile aspect for Target (device graph). I believe that is doable via API calls according to Target API call (https://developers.adobetarget.com/api/#updating-profiles). And given it's an API call, yes it is possible to be invoked within a Firefly Application.
Sarah