Thanks for the reply. Your suggestion is exactly what I was trying to do, but is not working.
I think there are a couple of issues going on.
Firstly/ Mounting through the File explorer (Nemo) does not appear to create a conventional mount point, but a temporary file system (tmpfs) instead. I should add this is mostly beyond my pay grade, I just want it to work.
The location given by the File Explorer is:
But it appears in the file system as:
And mount shows it as tmpfs.
Using Octave 5.2 (native) I can navigate to  through the Octave 5.2 File Browser pane, but not . However addpath fails with  & . Perhaps due to syntax checking.
warning: addpath: server=diskstation.local,share=generalshare/Octave: No such file or directory
warning: addpath: /run/user/1000/gvfs/smb-share: No such file or directory
Secondly/ Using Octave 6.2 (flatpak) I cannot navigate to the location at all using  or . I presume the flatpak environment does not support tmpfs, perhaps someone can confirm that.
I assume only a conventional mount is going to work, but I didn’t want to do that if I could avoid it.
If anyone has a cheaper work around I’d be glad to hear it.