VST plugin state is a binary blob owned by the plugin (the host's job is merely to read/write from/to disk when required). This is because the plugin is free to have hidden state that the host does not know about.

AAX and VST and AU [ and other ] plugin formats do not require any kind of interoperability of the way their plugin state is serialized and deserialized. Pulling the VST binary blob from a session in one DAW and giving it to the "same plugin" in AAX format running in ProTools is not even a thing.

Not only that, but even identifying "the same plugin" is far from trivial because different plugin formats use entirely different models for identification. The fact that the session in DAW A uses a VST format plugin identified as "XXXX-YYYY-ZZZZ" gives you no clue how to identify the equivalent plugin in LV2 or AAX or AU formats.,