No, I haven't tried to poke a hole in a sandbox. Generally speaking, if I have a choice between pacman -S <app> or "install with Flatpak and then fiddle with sandbox settings" I opt for the former. I get that you think this is important, and Flatpak is a nifty idea, but in terms of usability, it has failed me repeatedly to the point where I don't want to use it, so I don't.

You seem to be coming from a position of "Flatpak good, so everyone must use it", which is nice, but it's naïve. Flatpak is ok, but it has usability problems, and since you want people to use it, usability is kind of important. It also introduces a frustrating divide from a user perspective. The idea that "desktop apps" should be installed via Flatpak, and everything else with a proper package manager is madness from a user's perspective. I don't understand how you can't see that, but you're going to have to accept it 'cause newsflash: not everyone thinks like you.

Finally, packaging for Flatpack is a Pain In The Ass. I say this as someone who's tried it. The build system is clearly biased toward particular use cases and particular languages, which is great if you're in that camp, but for everyone else it comes across as impractical for the intended purpose.

So yeah, it's great that this is important to you. Go ahead and develop the shit out of Flatpak, and maybe even work on the user experience some more. I'll keep having a look from time to time, but for now, it's not happening, and this attitude of yours, that the rest of us will just "need to adapt" to your preferred way of working... if I wanted that I'd use a Mac. GTFO.