> Pegasos AGP 2x

As I wrote, Pegasos II has AGP 1x only. AGP 2x cards run at 1x speed in Pegasos II.

> More difficult are ATI HD AGP [...] It's needed to create a right
> ROM Macintosh ... not so easy I think.

Yes, that would be an obstacle which would have to be overcome from within MorphOS I think, if possible at all.