This has been mentioned once or twice by community members. Last night it seems NCommander actually tried it, following this ancient guide (https://fywss.com/plan9/info/next.html).
Watch (in horror?) here:
(Spoilers: he uses QEMU rather than Previous. Boo! But maybe the results could be useful as a starting point for bringing similar work to Previous.)
Snooping around NCommander's Discord, I determined that this was, in fact, a very recent development on the QEMU front: https://github.com/blanham/qemu-NeXT/
QEMU-NeXT seems to be specifically focused on NeXTstation emulation at present, with major attention spent specifically on this Plan 9 feat; it lacks DSP, MO, or printer support, but does have some facilities specifically for helping with the 9p netboot procedure. I am unclear on exactly what this entails; it might be as simple as letting another service punch through SLiRP.