Proton uses XWayland, this is for proper, native Wayland support. It will make its way to Proton eventually.
Depends on which DE in which version it is using, but anything with recent Gnome (Fedora, Ubuntu) will. Not sure if KDE distros generally default to it, and for more niche DEs the answer is probably "no", unless it was explicitly made for Wayland.
I doubt it's ever going to be a part of the core protocols, but it doesn't have to be, you can just use Waypipe.
I did, yes. TBH it is very anti-Matrix right out of the gate, makes a mountain out of a molehill and it even admits that it contains FUD.
There's a couple of things that are misleading in it (for example the section on bridges) and the critique basically boils down to "if you use the identity servers that are run by Matrix.org with your self-hosted homeserver they can see the info you send to them" and "Google Analytics in Element is bad".
All in all I didn't find it very convincing, and very lacking in nuance.
Can't Waypipe do this?
It is supported by systemd to use FIDO2 + pin to decrypt luks partitions with many security keys, including Yubikeys. I use it every day on my laptop.
Ordinary DNS requests are always plaintext and readable to anyone between you and the DNS server. So regardless of which DNS server you use, your ISP can see all your DNS lookups. For any amount of privacy for DNS, the minimum is something like DNS-over-TLS or DNS-over-HTTPS, the latter of which Firefox uses by default in some countries and supports everywhere.
I guess that depends on which power your agenda aligns with. That power is generally a safe choice, compared to services from a power where your agenda is orthogonal.
Seems like a solid bunch of iterative improvements!
Because Pipewire only handles and understands media streams, so it can stream the output of a window or the whole desktop, but only because the Wayland compositor has already composed the windows and other data it gets from the application to a visual and hands the final result to Pipewire.
That seems like a shortcoming in those tools, that I'd expect them to fix as Flatpaks are pretty commonplace.