Not that I’ve tested this (nor having intention to do so), but please download /devuan_chimaera/desktop-live image and follow this guide: Devuan GNU+Linux -- Software freedom, your way. Also, please do not forget to create: https://forums.puri.sm/uploads/default/original/2X/b/bd58ca2096fa169b2bfe59f1f349d19e131d09e5.jpeg, as described here: Installation failed - please help - #7 by Quarnero. Hope this helps you.
While this correct just follow above guide (not quite the same as Calamares installer but thing is … to make this thing work on your Librem 14).