Check the Linux Mint Cinnamon and MATE "Start" menus' context menus for apps because I think they have uninstall (and rating, but I'm not sure if it has a sharing option) items.

[Drew Naylor]

This will help for the All Apps list to make it all complete, yeah. Maybe the Plasma desktop menus have it, too. This would require abstractions for various package managers, and if a specific package manager isn't available, it won't have the extra items. Flatpak might be easier to manage.

Edit: I found it here: https://github.com/linuxmint/mintcommon/blob/master/usr/bin/mint-remove-application
It'll have to be modified to at least use QtQuick and QML, but I'll also have to make it compatible with other package managers as stated above.

Edit 2: It imports this script I think, so I'll have to figure out a way to not have to have it if possible. Seems to only use one function from it I think, but I may be wrong, but then this script calls possibly something else:
https://github.com/linuxmint/mintcommon/blob/master/usr/lib/python3/dist-packages/mintcommon/aptdaemon.py

Edit 3: Maybe PackageKit could be used to handle non-Flatpak apps? I really don't want to deal with Snaps, though, so I just won't. Will need to have some way to know if an app is a Snap, though, but I should be fine if I don't load Snap .desktop files in the first place. Or maybe I shouldn't use PackageKit and just figure out how it knows which package manager to use per distro, then run the appropriate commands.