Purism ships Debian-derived PureOS, and used to ship QubesOS. Now, Qubes is not really an option. I don’t know the full story, below posts give some background.
https://groups.google.com/forum/#!topic/qubes-users/2GfyEz0eYCE
https://puri.sm/posts/2017-07-shipping-update-for-qubes-orders/
https://forums.puri.sm/t/no-longer-listed-on-the-qubes-websites-certification-page/1050/5
https://www.qubes-os.org/news/2015/12/09/purism-partnership/
https://www.qubes-os.org/doc/certified-hardware/#qubes-certified-laptops
https://www.qubes-os.org/doc/system-requirements/
https://web.archive.org/web/20170506112157/https://www.qubes-os.org/doc/certified-laptops/
Firmware Security 