For some reason I never considered this route, despite following the PS5 Linux developments... is there a specific reason that the XSX is harder to homebrew than the PS5?

It would be incredible to convert my dusty XSX to a linux box

> is there a specific reason that the XSX is harder to homebrew than the PS5?

Xbox 360 was notoriously hard to reverse engineer at the time. Maybe for similar reasons.