It feels like this announcement is missing a step though. What can we do with this? Does this allow plugging your phone into a monitor and then running your phone apps in larger windows (eg, the opposite of what's shown in the videos). The idea of having the same programs running on your phone and laptop is nice in theory, but I'm quite happy with my own custom Linux setup on my laptop, I don't want to install PureOS on there.
Of course, much more work will need to be done in other programs to support this. The Gnome Web example looks really slick, and it's great to see this sort of 'responsive design' applied to native application interfaces - Android took a step backwards in this regard. But on desktop I'd rather use Firefox, and they have entirely separate builds for desktop and mobile. I wonder if Mozilla have any plans to support this?
PureOS is just Debian with a few tweaks. This work is being done as part of the GNOME mainline branch, so any GNOME user is going to benefit from it down the road. And as "alternative" Linux desktops (MATE, Xfce, LXDE) transition to GTK3+, users of these environments will likely be able to make use of it, as well.
Good to see that Gnome are involved in this themselves too, and it's not some Purism fork of Gnome.