Hey there is no update on this. Generally you don't get new features in ArcGIS Enterprise without updating. If your Portal is version 10.9.1 then it won't work. You can try if you have Portal 11.x but don't get your hopes up.
Here is an explanation on enabling registered services in case you want to try anyway but you need to have a high level of control over your ArcGIS Platform as well as the correct rights and you need to know what you are doing. Generally the registering of an datastore is done by the person that manages your GIS platform backend so if you are a normal user you might not be able to do this.
You need to have access to the ArcGIS Server Manager, login there and navigate to site -> Data Stores. There you register a location that is reachable to both your local pc and the ArcGIS Server. These locations are generally network drives that are used by multiple people in the GIS department (that way you only need to register 1 drive to enable multiple people to register their data). Use the validate button to check if the connection is working. Copy your File Geodatabase to this network drive. Open ArcGIS Pro and fix your project so all layers look to the data source on the network drive instead of the one on your local drive.
When you publish you service from ArcGIS Pro you have the option to reference or copy your data, choose the reference option (see attached image).
