I don't know much about Scribus, but a little bit of Googling shows that it should be able to open/import InDesign IDML files. There is an IDML file included with the InDesign pocketmod template, so this may be a workaround.
A member registered May 07, 2020 · View creator page →
Creator of
A Legal-Horror Handbook for Mothership
The Premier Module Anthology for Mothership
A Mothership Class for Corporate Spy Games
An Expedition into Hell for Mothership
An Occult Mothership Funnel
A collection of six backgrounds for Troika!
"A cloud of dense smoke surrounded it, and its eyes blazed like flaming coals."
A Simple Planet Generator for Spell Jammin'