The link is interesting because these emulators seem to be part of the standard distribution of 9Front. Most likely those are written from scratch, given that Plan 9 is not a POSIX system (unless they are using http://doc.cat-v.org/plan_9/4th_edition/papers/ape).
Edit: it's A POSIX Environment, but it still contains features that are unnatural in Plan9 and could by bypassed with more work, so much like emulation.
Ah that's the info I was missing, thanks! Indeed very interesting that emulators are part of the distribution.
The bug list is pretty darn unacceptable for a usable emulator.
You can’t even emulate PAL region games.
It’s a nice novelty that this is built in to the OS but the Linux/Android retro handheld scene is so much more wildly sophisticated than a half-broken command line emulator. Just jump on YouTube and search for an OnionOS overview to see what I mean.
Probably they would run faster and that's it.
Also, you can't compare GNU/Linux with 9front.
Why can’t I compare them? If someone wants to emulate games they ought to compare operating systems. Like I said, cool that 9front has a built in emulator, but that doesn’t mean it’s a good use case of the OS.