When running a report, or looking in NPM, my Linux machines are being listed as net-snmp-Linux. Windows machines are listed properly. Am I able to poll the correct distro and version without using a Linux agent?
You'd have to create a custom poller using Device Studio. Settings (All Settings) > Manage Pollers.
They also talk about doing that on this Solarwinds Lab
https://thwack.solarwinds.com/docs/DOC-176961