I bought a random EPROM off eBay and read it out with my Relatively Universal ROM Programmer, turns out it contained a BIOS for the Arche Triumph 88 - an XT clone.
https://wiki.preterhuman.net/Arche_Triumph_88
I'm attaching the ROM here in case anyone will find it useful. Only 8KiB, I'm not sure if that's normal for an XT BIOS.