Hello,
Xillybus' driver is part of the Linux kernel since version v3.12, so Debian 12's kernel definitely supports Xillybus. However, Debian's maintainers have not enabled this driver in the configuration of the kernel that starts out of the box. So in that sense, Debian doesn't support Xillybus.
Actually, I should have said drivers and not driver, because there's XillyUSB too. But never mind that.
A request to rectify this was sent over a year ago:
https://groups.google.com/g/linux.debia ... FLdiJH2YI8I've also contacted the maintainers directly, and it turns out that they're too busy to take of this thing. Maybe if other people join this request, something will move.
Regards,
Eli