I can find absolutely no information about this aside from confirmation it exists. How do you install it? How does it avoid being torpedoed by patch after patch aimed at stopping people executing arbitrary code without having coughed up the funds to become a registered developer?
At this point we're into the realm of "what do you want to see"—I'm not excited by the prospect of 721 hacks or Drayano-style difficulty hacks, which would seem to be all you could do without touching a 3D model.
I'll certainly agree that that's pretty much all we can do with hacking at this point, but it's not so much that we aren't capable of delving deeper so much as that we just haven't due to a general lack of interest (as it stands) and that the emulation and ease of downloading the games just isn't all that convenient. This could change and we could delve into scripting and like. Would we anytime soon? Probably not, especially considering that what is asked of the hacker for something like this might not appeal to/might scare away the many potential Pokemon hackers that exist today. After all, the GBA Pokemon games have very easy entry points. So the possibility's there, but it probably wouldn't be these hackers that touch them.
As for HANS, there's no official thread for it because Smea basically just released it in the Homebrew Starter Pack for the homebrew launcher. No installation, really, and it can't really be affected by patches, pretty much the only thing that managed to get around it once was the eshop, due to how it works (though I believe that's been resolved).
He did a video, though, that documents its usage. In the past I used it to play...Little Battler's Experience? That or Yo-Kai Watch, whichever required an update and was released after HANS.
I just don't think the positives, of which there are barely any, outweigh the negatives. It would take years for DS/3DS to catch up to GBA, and that's assuming everyone just decides to switch for some unknown reason.
I agree with you on the point that Pokemon GBA's more attractive because it's easier to get into (well, easier all around, really) and we've got years upon years of experience. This, though...there's a lot of potential as far as Gen 6- or even Gen4/5 go. Potential that literally cannot be tapped into on the GBA or, more specifically, on the Pokemon games on the GBA. As astounding as it is, the things people have been able to do and what we know about the games, I wouldn't say that the positives for the post-GBA titles are minute in any way, especially since we don't really know the extent to which they can be manipulated.
I'm not saying we should all jump ship and hack those, though- not at all. Said this above, but the people who'll be hacking Gen 6 will not be the same people hacking Gen 3, and it's not all too dissimilar from the split between the Gen 1/2 and Gen 3 hackers. I mean, the hacking landscapes and obstacles for 3-6 and 1/2-3 are completely different so I wouldn't say they're the same, just that they have similarities in terms of who hacks what.