I do like Flatpak, for the most part, though I wish that the distribution and the sandboxing parts of it were not tied at the hip.

The sandboxing would be an easier sell if it allowed interconnections between apps as appropriate. Yes, I do want KeepassXC to be exposed to the KeepassXC extension in Firefox. Yes, I do want yabridge to expose VST instruments to BitWig. We don't want to be hardcoding support for individual pairs of apps either, so the mechanism would have to be generic.

Abstracting away filesystems also only goes so far. Running Filelight sandboxed for instance is just too slow to be useful.

And the distribution would be an easier sell if it allowed for standalone app downloads without going through a centralized hub with dedicated download tools.

Hopefully these are things we'll eventually see solved. Until then, it's still pretty damn good to be able to install many common apps regardless of distro specifics. An easy thing to take for granted, that. Used to be the answer to installation woes was "what's so hard about tracking down every dev dependency and compiling it yourself?" and it's nice that we're firmly moving on from that.