Anytime they have been pressed for details on other platforms they decline to comment. Why would they do that if they could speak freely about it? The only comments they are providing at this time are super vague like the ones you mention.
They build the demo according to them for the PS5 and while it probably runs on basically anything already like they say that demo was made especially for PS5 and tailored around its hardware and is probably optimized to a much larger degree than on anything else. Talking about how this demo runs on XsX not specifically build or optimized for that hardware might not be the best idea for instance?