@eugenio, core team member of Droidian, had the idea of dual-booting Droidian and SailfishOS a long time ago and even did some experiments, but this was not tested in depth, nor documented. It now is! See instructions here: https://gist.github.com/Kabouik/94e9e60d84c0eeae9d48e18c11ed419e I am not pasting the how-to here, just the URL, so that there's only one place to edit if changes have to be made in the future.
This may work with other secondary OSes with some slight changes, or with the Pro1x (where the extra storage could be handy), but was not tested so far. I chose to do that on th