1. Just works
yes same here and it's plug-and-play from there you get a launcher icon and it should just work.
Please checkout babyWogue's channel for more on flatpacks; https://www.youtube.com/channel/UCZWadyLVO4ZnMgLrRVtS6VA
The hate on sandbox seems a bit overblown as well. If you think about how android apk have permissions its essentially the same thing: instead of allow full user access it is given an api to talk to that can be blocked by the users (e.g. camera, user files..), this is something that is part already on flatpaks and GNOME Software and part in the making.
3. Hate on GNOME
In the end GNOME is/will be the DE to rule them all. If you don't like it add the addon
dash-to-panel. (I highly recommend PopOS with auto updates for non tech family, they generally get things right with sane defaults)
4. Linux is secure
IIRC you run a deb file that runs
rm -rf ~/ it will run. Sorry but that is not secure (google-chrome even adds a file to cron 😨). What is secure is the, handpicked, vetting process of the distro/repo.
5.Why flatpaks are better than snaps
One can only be used if Ubuntu keeps going, the other has the ability to add repos from other sources.
Please check your facts before hating.