I have two app registrations for two different projects in Azure Active Directory. I also created two Power BI Embedded instances. I only have access to a single subscription in this account. Is there a way to assign a single instance for each app?
In the PBI embedded capacity resources in azure, you can add/remove users/SPNs(apps) as PBI capacity Administrator.
PBI capacity Admin gives you the ability to assign that PBI capacity to a workspace.
e.g, If you are given the capacity admin, then you can assign that capacity to any workspace in which you are part of the admin. You can achieve the same thing for SPNs using REST APIs
For more details on how to use the Capacity you can refer here