XMOS processors are certainly curious devices.
And no, they are not powerful enough to emulate parts of the Amiga chipset.
But I have seen one doing a pretty credible imitation of a C64's video display generator.
And, one of the ways I came to suspect the Paul Gentle had a hand in the X1000's creation (before it was announced) was the PA6T processor used and the presence of an XMOS processor.
You see, Paul's firm had already done work with the PA6T AND Paul had published an XMOS based sound card design.
Anyway, think of it as an mcu like device added to the motherboard, flexible, but not too powerful.