I think it’s still true Audacity supports mono and stereo outputs and that’s full stop. With the right software and connections Audacity can record multiple tracks and there is a support forum for that.
https://forum.audacityteam.org/t/multi-channel-recording-in-audacity/15644/1
I think Audacity recognizes what MIDI is now, but I’m pretty sure you can’t do anything musical with it. MIDI isn’t sound, it’s instrument machine control. Manufacturers hide that very well and everybody thinks they’re playing a MIDI song when what they’re really doing is applying MIDI instructions (press key number 53 on a Grand Piano) to the computer’s internal sound generators and then playing the result to the sound system.
Since Audacity is a sound editing program, someone would have to write and integrate MIDI services—with all three operating systems in multiple languages.
Are you a volunteer developer? All are welcome.
Koz