> I used to think Flatpaks were a huge pain the butt, but over the last few years, I moved to using them for all third party software
I am a Nix person who has been a bit obsessed with package management for a long time, and it's probably fair to call me a bit of a 'container skeptic'. I know many good reasons to prefer other means of installing packages, and I agree with most of them. I care about things like the extra storage overhead, the increased app startup time, the additional complexity associated with portals and sandboxing, the extent to which Flatpak applications do or don't support the available sandboxing features, and the orientation of Flatpak towards enabling a larger proprietary software ecosystem I'm not very interested in.
But despite all of that, and despite my interest in— and to some extent, commitment to— competing paradigms... I think Flatpak does what it tries to do pretty well. It seems to me that the engineers working on it have done a pretty good job of mitigating the downsides and risks, like library duplication and difficulty of shared updates, disk usage, etc. Considering what it aims to do, it feels pretty fast, reliable, and neat. And I trust it way more than an apt or dnf or pacman repo hosted by the likes of Zoom, Google, Discord, etc. It's a much better way to manage third-party software than anything else we've got.
I think it's clearly a good thing that the biggest and most popular desktop environments are coalescing around it. This is good news for desktop Linux users in general, and especially good news for those of us who don't run Ubuntu or derivatives. The more things are packaged for Flatpak, the lower the burden for practical usage of distros maintained by small or new communities.