In my opinion, encryption at rest is a minimal requirement for a phone. I know that the developers don't have a lot of time and a big wish list.

I found this guide here:
https://forums.ubports.com/topic/1012/one-method-to-encrypt-home-phablet/1

The thread is very old. Have there been any new developments?

I would assume that it's not the same device as the Nexus 5, right?