I think I too asked for a Help for the current project only (when developing for a Desktop application, I do not care about other targets / and because a project is still “locked” to a target: this is useless to show help for other targets).
Worst: if one day we will have “one project” → “multiple targets”, it will be easy to add CheckBox to select whet documentation to show…
But this day is not for tomorrow, I suspect a Xojo whole rewrite to achive that goal.
It would have another benefit: one can get original API as help (you know the old one that I used for so many years (more than 20 years)…