When using the “stage-packages” directive for a part Snapcraft uses the OS package manager to install the package. But, does Snapcraft execute a “full” package installation and configuration, just as the apt install command would on a full OS? And do all of the prerequisite packages get installed? Debug output shows that they do, but execution seems to show that they do not: lots of errors and missing library type stuff.
If not, where does Snapcraft differ?