X11 has effectively already been deprecated for years, seeing little to no development on it. No one should be surprised.
X11 is complete.
Wayland is incomplete, and is missing essential features like accessibility and automation (ydotool will never have half the features xdotool has).
Mozilla, for example, would sign Firefox’s flatpak with a PGP key that they would disclose on their website. You verify the signature using the RSA algorithm (or any other algorithm for digital signatures. There are a bunch.) Or, you could just trust that your connection wasn’t tampered the first time, then you would have the public key, and it would verify each time that the package came from that same person. Currently, you have to trust every time that your connection isn’t tampered.
Major flatpak providers (Flathub at the very least) would include their PGP public key in the flatpak software repo, and operating system vendors would distribute that key in the flatpak infrastructure for their operating system, which itself is signed by the operating system’s key.
Article doesn’t mention my biggest problem with flatpaks, that the packages are not digitally signed. All major Linux distros sign their packages, and flathub should too. I would prefer to see digital signatures from both flathub and the package’s maintainer. I don’t believe flathub has either one currently.
Sure, here are instructions for getting Linux Mint running: https://www.linuxmint.com/download.php
These instructions are for creating a USB flash drive that functions as both a live environment or an installer. If you don’t want to install it yet, this allows you to try it out while booting just from the flash drive, without modifying your hard drive at all.