When I searched about Supermodel libretro core, I found such a this post.
However, after over 4 weeks there was no sign of being pushed out, so I decided to building Supermodel core it myself. As a trial, I build psx and neocd, and started them on Retroarch and I was able to play them no trouble.
Next, when I built Supermodel, could not complete it with the error of “Src/OSD/libretro/Thread.o”.
I don’t have the skills or expertise to generate object.
And I hope that Supermodel core will be officially pushed out from libretro at your earliest convenience.