No DAWs involved. I am talking about small conferences where presenters are often "zooming in". They need to hear the mix I am sending to the PA minus themselves (hence N-1). That's how it's done live and even the most basic live desks offer post fader Auxes. So to answer your question - the destination would be the input of a dedicated zoom computer.
I tried this with my Babyface, where AN 1 would be the PA and AN 2 Zoom input. Now the mix of AN 2 needs to exactly follow that of AN 1 minus the Zoom output, because I don't want to send it back and create a feedback loop.
Of course TM is not meant to be a serious live mixer, but this is the last feature I am missing to make it work. Another way to put it is the ability to mix into multiple submixes at once. If I could select two or more outputs simultaneously in TM (for each input individually), that would be it.

Right-click onto an output channel and copy/mirror to other outputs let you connect multiple outputs to be one submix.
Every input can be routed individually to every output all the time.
For live mixing Totalmix is great.
Let's say an evening with a bunch of bands every soundcheck can be stored in a workspace and loaded for the gig.
You may have to spend more time to learn all functions and features especially Trim and Loopback.