Using a Xenia bios file is relatively straightforward:
Technically, You do not need to hunt down a specific bios.bin file to make Xenia run.
For Xenia Canary (very old versions):
While emulators for systems like the original Xbox ( xemu ) or PlayStation 2 require users to provide legally dumped BIOS files from their own hardware, Xenia uses to recreate the Xbox 360's operating environment without needing a direct copy of the console's internal software. Why Xenia Doesn’t Need BIOS