Can't use SNMP v3 AES-192 and AES-256 encryption?

The problem is that you need Net-SNMP lib needs a minimum of version 5.8 to support this modes.
And now only the actual distributions have version 5.8 (Ubuntu 20.04). Debian 10 has only 5.7 and will not work as an example.
As long as there are only very few distributions supporting this it will not be available i think.
For the enterprise edition it would be easier i think to implement it as the enterprise edition uses pysnmp directly.