From what I saw the #SNMP package supports only DES and (partially) AES128 privacy providers.
Are there any plans extend the list and support additional privacy providers? (like AES192, AES256 and 3DES)
As SNMP protocol officially only supports DES (AES was a draft), #SNMP itself won't support anything more. But you can feel free to port more providers from SNMP#NET, and use in your project.
As a very old post described, the current AES privacy provider was ported from SNMP#NET project,
https://blog.lextudio.com/2009/09/trident-sign-3-1-ready-and-next/