Support for Shell Extensions was removed from GNOME Software since 3.36 (because it was problematic and hard to maintain). I just checked it in the latest stable Snap Store app and was not able to find any support for Shell Extensions there.
So, I see three possible solutions for this issue:
1. Add downstream support for Shell Extensions to GNOME Software / Snap Store on Ubuntu. (That would bring too much work and possible issues, at least in my opinion.)
2. Add AppStream metadata file to the chrome-gnome-shell package that would display the package as Add-on for something (Firefox?) in Snap Store.
3. If a package from main cannot depend on a package from universe, move gnome-shell-extension-prefs to universe and add chrome-gnome-shell to its dependencies. (That would be the best solution in my opinion.)
Support for Shell Extensions was removed from GNOME Software since 3.36 (because it was problematic and hard to maintain). I just checked it in the latest stable Snap Store app and was not able to find any support for Shell Extensions there.
So, I see three possible solutions for this issue:
1. Add downstream support for Shell Extensions to GNOME Software / Snap Store on Ubuntu. (That would bring too much work and possible issues, at least in my opinion.) extension- prefs to universe and add chrome-gnome-shell to its dependencies. (That would be the best solution in my opinion.)
2. Add AppStream metadata file to the chrome-gnome-shell package that would display the package as Add-on for something (Firefox?) in Snap Store.
3. If a package from main cannot depend on a package from universe, move gnome-shell-