This is almost definitely the problem they're facing although I think that description is a little bit odd. It's missing the operative word: "portals". It's the XDG desktop portals service that is involved here. What you need to ensure is that you have a desktop portal provider set up that provides org.freedesktop.impl.portal.FileChooser. What's kind of neat about the way xdg-desktop-portals is architected, you can pick and choose different implementations for different services. This is especially useful outside of desktop environments where you might need to use e.g. the wlr provider for screenshots and screen capture, but you still want e.g. KDE file dialogs.

It's unfortunate that the documentation for XDG desktop portals (and generally, setting up a complete desktop setup when using compositors like labwc or Sway) is relatively poorly documented. I have my feelings about the pervasiveness of DBus services everywhere but overall I like desktop portals.

Apparently yes. I tried installing xdg-desktop-portal-gtk at first, but that didn't work. xdg-desktop-portal-kde did.

But now I get issues that are likely due to problems with downloading language server binaries and running them, as the parent comment indicated. When I open a Rust project it says "Language server rust-analyzer-2024-07-08 (id 1) status update: Failed to load workspaces."

Also, it dumps core every time I quit. :)

Well that got rid of the core dump each time I quit, and it fixed the language server issues. So together with the portals configuration it seems to be working as well as it can.

There's also this, has AUR-style *-git packages: https://www.nyx.chaotic.cx