Is it possible to resample the Tracker's audio output?

No, this is not possible. Tracker can't play its patterns and record audio at the same time due to its hardware limitations. It's not a matter of a firmware update. Such functionality was not really intended in a Polyend Tracker, trackers were not loopers, audio loop players nor audio recorders. Their workflow is based on short samples mostly.

One can use the "render selection" function in order to bounce steps or selections of steps from one or more tracks at the same time to a single audio file.

The simple rule is that the Tracker can’t both record and generate audio. But remember, MIDI is not audio. The Tracker will only play audio or record audio. Never both at the same time. You cannot hear the internal audio of your patterns while sampling the external input. However, while sampling, the sequencer will output any midi information that you’ve programmed into the sequencer if you want it to. It is possible to monitor the line input in stereo while internal audio plays but you cannot record it at the same time.