No offense, whatsoever, taken! Again, thanks for outlining the workarounds!
Somehow it passed over me that debian is providing packages for ublock (and some other addons). Personally, it’s something I won’t force on my users – they should install their own, preferred add-ons.
The one difference seems to be that (at least on debian stretch), there are no restrictions for users to install addons to debian’s firefox …
Stupid question (I know, I should search): is there a concise summary how purebrowser’s defaults differ from a vanilla mozilla firefox? (Assuming the same base version for both, i.e., 68.0.x)