Hi Josh - from the looks of it (@purism 's post 'Day 2 - Gedit & Apt') they have sudo apt install available to use on the phone - "You don't need to use apt. But you can. Which is awesome."
It would be an odd choice to be able to 'sudo apt install' but not be able to sudo apt update/upgrade, so it very much looks like a fully functional standard 'apt' will be there to use.
:)
@phelion @purism I just saw the video too and it made my very happy! @purism are making the right decisions!