I don’t understand how a transitional package that installs the snap (which is documented in the package description) is any different from a transitional package that replaces, say, ffmpeg with libav.

$ apt show firefox
Package: firefox
Version: 1:1snap1-0ubuntu5
Priority: optional
Section: web
Origin: Ubuntu
Maintainer: Ubuntu Mozilla Team <ubuntu-mozillateam@lists.ubuntu.com>
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Installed-Size: 124 kB
Provides: gnome-www-browser, iceweasel, www-browser, x-www-browser
Pre-Depends: debconf, snapd (>= 2.54)
Depends: debconf (>= 0.5) | debconf-2.0
Breaks: firefox-dbg (<< 1:1snap1), firefox-dev (<< 1:1snap1), firefox-geckodriver (<< 1:1snap1), firefox-mozsymbols (<< 1:1snap1)
Replaces: firefox-dbg (<< 1:1snap1), firefox-dev (<< 1:1snap1), firefox-geckodriver (<< 1:1snap1), firefox-mozsymbols (<< 1:1snap1)
Task: ubuntu-desktop-minimal, ubuntu-desktop, kubuntu-desktop, kubuntu-full, xubuntu-desktop, lubuntu-desktop, ubuntustudio-desktop, ubuntukylin-desktop, ubuntukylin-desktop, ubuntukylin-desktop-minimal, ubuntu-mate-core, ubuntu-mate-desktop, ubuntu-budgie-desktop-minimal, ubuntu-budgie-desktop, ubuntu-budgie-desktop-raspi, ubuntu-unity-live, edubuntu-desktop-gnome-minimal, edubuntu-desktop-gnome, edubuntu-desktop-gnome-raspi, ubuntucinnamon-desktop-minimal, ubuntucinnamon-desktop
Download-Size: 77.3 kB
APT-Manual-Installed: no
APT-Sources: http://us.archive.ubuntu.com/ubuntu noble/main amd64 Packages
Description: Transitional package - firefox -> firefox snap
 This is a transitional dummy package. It can safely be removed.
 .
 firefox is now replaced by the firefox snap.