Disclaimer
Flatpak uses OSTree, like Fedora Atomic Desktops (Silverblue, Kinoite etc) and similar to BTRFS snapshots.
So many files are deduplicated and linked, not actually there
https://gitlab.com/TheEvilSkeleton/flatpak-dedup-checker
50GB without
31GB with deduplication
21,4GB with BTRFS compression
What distros are you talking about? Even if install all available DEs, any distro will take ~10 GiB or a bit more. Default installation is much smaller.
I remember at the past my allready running distros were always 20-24gb. With allready most apps installed. Like Mint and Workstation. Maybe my memory is not that good and I am wrong… I actually can not say how much is my current Silverblue now, somewhere around 20gb.
What I wanted to say, Flatpaks sure pull dependencies, but with lots of Flatpaks your next app will be small, like 2gb or maybe 800kb. With atomic distros Flatpaks make even more sense.
There’s no any magic that could reduce Silverblue size, it is based on the same packages as Workstation. Only the installed subset of packages can differ.
Like gnome-tweaks, if you install it in toolbox, it will pull 300mb of dependencies and once installed it is 900mb. Is it magick or 900mb less? Gparted is also missed in Silverblue and not available as flatpaks. Also some magick or anothe MB’s?
Yes, it’s kinda magic if you are unable to remove them in non-atomic distro.
But gnome-tweaks removed from Workstation wont free you 900mb lol. Other apps need those 900mb dependencies too.
I remember when I used to keep my fully configured distros below 700MB so I could just dump it all to a CD as a backup. Good days.