Hello,
As a long time TAILS user and advocate I find your project interesting, if possible could someone from your dev team provide a breakdown of comparison between PureOS and TAILS?
xx
- Catie
PureOS is (like TAILS) also built upon Debian, and is more like a standard GNU/Linux distribution with emphasis on free/libre software and improved privacy and security, which you can install and customize. On the other hand, TAILS is a specialized (security and privacy wise) GNU/Linux OS meant to be used as a live system (you run it from a CD/DVD/USB), which by itself means a low “privacy footprint”. But you can also manage to reduce that “footprint” with any other linux distribution, with the help of Tor, Tor Browser (+ some addons) and some tweaks and good security practices, it just that TAILS provides all these by default (hassle-free).
However, I would advised you to carefully read their disclaimer: https://tails.boum.org/doc/about/warning/index.en.html
The first item there, “Tails does not protect against compromised hardware”, is exactly why you need Librem. 
And to tell you the truth, I’ve never used TAILS, but reading through their documentation I see that almost all these I have on my linux box, except for the Tor+TorBrowser. I’ve even setup alternative DNS (https://www.opennicproject.org/) on my router which is runned by Linux (DD-WRT).