python3-ubuntu-image
xubuntu-desktop
xubuntu-core
vanilla-gnome-desktop
ubuntustudio-desktop-core
ubuntustudio-desktop
ubuntukylin-desktop
ubuntu-unity-desktop
ubuntu-snappy-cli
ubuntu-snappy
ubuntu-mate-desktop
ubuntu-mate-core
ubuntu-core-launcher
ubuntu-budgie-desktop
snapd-xdg-open
snapcraft
snap-confine
qml-module-snapd
plasma-discover-backend-snap
lxd
lubuntu-desktop
libsnapd-qt1
kubuntu-desktop
ember
cyphesis-cpp
chromium-browser
ubuntu-server
ubuntu-desktop-minimal
ubuntu-desktop
ubuntu-core-snapd-units
livecd-rootfs
maas
apparmor
libsnapd-glib1
gnome-software-plugin-snap
command-not-found
Any of these packages is going to pull snapd in if installed. Soon after writing the above comment, I decided to install chromium, and ... snapd got installed as well as a result. I guess I should double check each claim I am about to make, BEFORE making it.sigh...
Edit: Please note that many of these are "leaf" packages, by which I mean that no other packages depend on them.