The answer is "kinda". I'm not sure how Rockwell does it's export. Because a Portal project can have multiple PLCs, HMIs, drives, etc, and each is a separate device, it may think about the data a bit differently.
There are a few options:
1) Copy/Paste from a reference project
You can open up an old project as a "Reference Project" which is essentially a Read Only project open in the same instance of Portal. You can grab all the IO devices in the HW config and copy to the new project, then assign them to your new controller(s).
2) Create a Library
If you have a HW setup you use all the time, you can drag the objects into a library. This keeps all HW parameters. You would need to reconnect them to the new PLC in the new project, if you don't want the PLC included with the rest of the IO.
3) Export/Import CAx data.
This is the one most similar to the old Simatic Manager function. It is compatible with the TIA Selection tool (great for building a quick BoM), as well as EPLAN, if you use that for ECAD. If you export CAx from Portal, it exports the part numbers and tags, but not PLC code. When you import, you have choices about how to handle potential naming overlaps (overwrite, keep old, rename new devices).