PureBrowser ships with uBlock (Origin?) and HTTPS Everywhere in PureOS 8 Beta 1, but is missing a number of really important privacy extensions. That discussion is for another place, but users should be able to quickly add other extensions of their choosing. When I try to install addons via the menus, the "Mozilla Addons" site tells me I need to install Firefox.
I'm specifically thinking about extensions like:
DuckDuckGo Privacy Essentials, Decentraleyes, Privacy Badger, Privacy Possum, Exodify, TOS;DR, Polisis
...but there are also others that make it easier to live in a world that's dominated by other platforms, like User Agent Switcher, as well as development addons like Web Developer.
This may or may not be related to T247, and perhaps should be fixed on the Mozilla end since PureBrowser identifies as Mozilla / Gecko / Firefox before it identifies as PureBrowser.
An alternative approach, which I would not recommend given our current bandwidth and resources, is a "PureBrowser Addons" repository to duplicate Mozilla's. Trisquel tried something similar with Abrowser and, as I understand it, the work of auditing addons and then hosting them outside of Mozilla's servers was tedious and contentious.