This might be because I am just plain stupid, and others in the snap community that I have asked on Twitter have just ignored me, so it might be the case. If so, I deeply apologize in advance.
In KDE Neon with tcsh as shell I have no GUI way to start apps. They do not show up in the plasma menu, nor can I start them via the launcher [Alt]+[F2]. Finally, I have been able to start them via “snap run”, but that feels a bit unintuitive if it is the only way.
So please point me to the simple solution that I have overlooked, or tell me how I can help mend this oversight.
Snapd drops a file at /etc/profile.d/snapd.sh (probably ignored by tcsh) and adds relevant entries for user-session envnrionemnt generators. AFAICT this should work in most cases. Can you run the following commands in a terminal and paste their output:
Clearly something is off here. There is an entry in $XDG_DATA_DIRS, but none in $PATH. Can you confirm that /usr/lib/environment.d/990-snapd.conf exists in your system?
Perhaps, there’s something overriding PATH in your environment. Unfortunately there’s many ways in which it could get broken. I would suggest looking at any other scripts in /usr/lib/environment.d that run after 990-snapd.conf, perhaps your profile setup too.