Would it be possible to install the Blackphone OS on the FP, somehow?
The sort answer is no.
I like what they are doing but I have not seen code being released by them yet. Secondly the apps they are using, Like text secure, currently do not support our dual SIM feature. Best for now would be to try and help out on the CM related work or try to get things rolling on non Android ports like Ubuntu or Firefox OS.
You may wish to contribute on the following questions elsewhere in the forum: