Documented this issue in the wiki just now.
Install Additional Software Safely
Quote at time of writing (might change in the wiki - not here -in future):
General forum discussion about snap: Snap Store / snaps / snapd / snapcraft.io - a new software source? [archive]
Qubes-Whonix ™ issues:
- Efforts to persistently install snap apps in Qubes-Whonix ™ via bind-dirs [archive] or with snap proxy settings have proven unsuccessful. This means it needs to be installed in a TemplateBasedVM on every occasion it is required. Efforts to improve this situation are most welcome, see: Wickr Me vs Qubes-Whonix Persistence [archive] and snap totally unusable on Qubes whonix-ws [archive].
- Qubes TemplateVMs are non-networked by Qubes default. (APT works because of Qubes’ qrexec-based updates proxy.) Therefore snap does not run inside whonix-ws TemplateVM. The same would probably also happen in any other Qubes TempalteVMs such as for example in a Debian TempalteVM. As per Free Support Principle is recommend to make snap work in a non-Whonix based TemplateVM first such as a Debian TemplateVM before attempting to do the same inside Whonix ™.