I have to admit that Flatpak's runtime deduplication is impressively good, despite preferring the Nix approach.

It's a shame to hear that kind of talk coming from the openSUSE world when Zypper did so much to raise the bar for high-level Linux distro package management tools. :(

openSUSE does an awesome job getting a hell of a lot of mileage out of RPM, from the vendor-based repo management to BTRFS snapshots to the huge and powerful (cross-distro!) automated build service.